To learn electronics in a very different and effective way, and gain access to Mr Carlson's personal designs and inventions, visit the Mr Carlson's Lab Patreon page here: www.patreon.com/MrCarlsonsLab
@@Daveyk021 on a 4 stroke engine it takes 2 revolutions of the crankshaft to fire all the cylinders. the configuration makes no difference. 3 cylinders fire on a 6 cylinder engine per revolution and 4 on an 8 cylinder.
@@richardcranium5839 Thank you. Also the distributor runs off the crank. I think this morning, I was in lala land thinking the cam shaft. Since a V engine has two, I was thinking that would change the math. I thinker on cars and small engines (when I have time). I need to check the math to test a TAC and DWELL meter I have (it is digital, so it is probably dead nuts on??). I still like the idea of an analog meter for it. I think that is better to watch the needle swing. I may get on ebay and order and old analog tac/dwell meter before they are all over $1000 after too much of the public see this video.
@@Daveyk021 V engines can also have only one camshaft. They were the older engines that had pushrods and lifters. The camshaft was in the block right over the crankshaft.
@Andrew_koala I think you got it spot on. I don't have the hands-on knowledge on the subject-matters Mr. Carlson shows us (very little practice, I only got the theoretical electromagnetism part of it), but I admire the simplicity and practicality he demonstrates in every video. Also, I really appreciate the old and new equipment he shows and restores (we never saw 99% of those brands and products in Brazil).
My father had a tach/dwell meter, (which is still (probably) in his garage ;-), that he used to make fine adjustments to the points on his 69 Imperial. They used to call me "Mic Eye" when I was younger cause I could adjust the points without a feeler gauge. (I couldn't really tell the gap, but I had done it so much that I could get it REALLY close, so close that dad rarely had to adjust them once I'd set them) Thanks for the trip back in time Mr Carlson!!! I sure do miss my dad!!!
Just finished fixing up a Canadian made Tuffy Tool model 1813 Tach-Dwell meter , thanks to this video. Having access to a function generator was able to calibrate rpm and dwell accurately. Was out by a bit due to out of tolerance resistors , linearity is perfect across the whole span of the meter. I use this for my Canadian ' 66 Malibu SS . Still running points as the car still has its original 283. Great Job Paul !
For those wondering why 'dwell' matters in old cars with breaker point ignitions: The dwell angle is the number of degrees of crankshaft rotation in which the points are closed. During this period, the magnetic field in the primary winding of the ignition coil is building. When the points open, the magnetic field collapses quickly generating a brief high voltage, which is stepped up even more in the secondary coil eventually arcing across the spark plug gap. The longer the dwell angle (i.e. points closed), the more time there is to build a magnetic field in the primary - an increase in this magnetic fields leads to a higher voltage at breakdown and a better spark. The dwell angle is set by adjusting the breaker point gap - i.e. how far apart the points are when they're pushed open by the cam lobe. A larger gap implies a smaller dwell (inverse relationship) because the breaker points in the small dwell case are adjusted such that they open sooner on the cam lobe and are ultimately pushed farther apart at the top of the lobe. Because breaker points can be pitted due to arcing, adjusting the points gap distance (with feeler gauges) is relatively inaccurate (as the points faces may not be flat) and having a dwell meter does a much better job at getting a proper adjustment. Incidentally, I believe vintage race cars occasionally used dual point systems (and possibly additional coils ?) to maximize coil charging at high rpms - a scheme where every other ignition cycle would take place on the alternate coil/points set that would be fully charging during the previous cycle. I may have the details of this last part wrong. Anyway, I hope this is interesting/helpful to someone out there :-)
The ignition dwell angle isn't derived from crankshaft rotation. It's is derived from distributor rotation. Crank rotates twice the speed of the cam. For example a 4 banger has breaker lobes that are 90 degrees apart, so the dwell angle would be around 45 degrees.
@@dak682 More modern vehicles will have gone to electronic ignition, which usually uses the car's onboard computer to measure the RPM directly, and then decide when to fire. As long as it's working correctly, it's got less moving parts to deal with and less calibration needed, as well as allowing for variable ignition timing through all RPM bands and air temperature conditions with more advanced vehicles. The biggest downside is that especially in 2021 cars, nothing is really user/owner-serviceable any more.
This is all new to me and I've driven lots of old cars. I'm off to a new video to fill that gap. Need to learn about dwell. I never fail to learn something new from these videos.
When I started doing mechanic work over 50 years ago that was the tool to have to get your car is running great. I really enjoyed this video. It’s because of videos like this that I became a patron sometime ago. The only thing I can use my old dwell tachometer on is the tractor.🤣👍 I look forward to all your videos. Keep safe Paul.
This video was on the mark as I just purchased an almost identical Sears meter with an additional range for voltage. The meter needs calibrating so your video was just the help I needed. Thanks so much Mr Carlson.
Impressed is somewhat miss-understated, I really did not expect this 'Pro'! meter to be anywhere near as accurate, (so much is labelled 'Pro' now days and it means crap really) hats off to the designer and manufacturer, they really came up with something quite special, obviously the meter movement is of quite high quality not something you would get today unless you pay 'think of a number and double it' price, the old school stuff wins again, thanks very much for showing this Paul it was VERY interesting to watch and see it truly shine at the end!
My lifetime career was in electronics! 3 years at Westinghouse, 18 at Kodak and 12 at Rochester Institute of Technology! Loved my life’s work! Over those years I collected dumpster dive test instruments bound for the recycler! Most need repairs!! Want to fix them! Ha ha! Thanks for the videos!
@@MrCarlsonsLab I have a 67 Mustang and 72 VW beetle and I still have my old Dixco tach/dwell meter to adjust ignition timing! Now I know how to calibrate it! THX! I’m also restoring a C64 and disc drive, fixing some old cb radios and building cb antennas! I’ve been retired 8 years but I try to learn something new every day! Thanks for that!!!
Knowing that you have moved the labs all around, it feels a little funny to see the old main lab in the intro and outro! Sears always had major manufacturers make their house brand devices. It is possible that the design really is a SUN product though it really does not matter. Nice job as is your normal! Even my "old" truck (1973) has electronic ignition so the dwell function to me is not needed. So many people today look down on the old way to do things. A needle is much easier to use when doing things like setting RPM as it is the way our brain works, analog not digital. Great job on a device I had totally forgotten about! NOW TO THE UFO device!!! :D
Thanks Paul,still have 3 old dwell tach meters that need servicing,when points rubbing blocks went from fibre to plastic you really had to stay on top of dwell angle and that little capsule of grease was ever important,changed quite a few breaker plates on old fords as the dwell changed quite a lot on them,amazing how much better they ran with steady dwell
Ive been looking for how to do this for ages. I have 2 of these. One is accurate and the other not and I didn't know how to fix it. I'm impressed with how easy this is to do. Thanks.
Thanks for the video. Sears tune up equipment was always very accurate OoB. I owned several over the years. In the 60's, the name they were sold under was Penske, as in Penske Racing Working on small sports cars, the most important readings were usually for low idle speeds. High speeds were not used as much, except for maybe checking your tachometer. The dwell meter was especially useful as that was the function that indicated the quality of your distributor bearings and points-springs. I was kind of hoping you were going to have to build in some calibration controls if this didn't have any originally. Please set aside some time in the future, to do one of those too. Thanks again.
I was going to congratulate you on 300k subscribers last week and didn't get around to it. So, congratulations on 301k subscribers! Thanks for your great videos!
Thanks Paul! Got out my old ArcherKit Engine Analyzer to check the calibration and sure enough it was off! That kit had you do the CAL of the tach using a line cord with a few 56K resistors in series with the Hot and Neutral. You plug it in the wall socket and attach your test leads to the ends of the resistors to get 60Hz (ish) line frequency. Got you close, thanks for the video and math to check the other RPMs!
Paul, As smart as you are I have to wonder if there is anyone that you look up to. Before I get any older I'd better start your electronics classes very soon! Thank you a thousand times over!
Had one in the early 80's with the wedge shaped circuit board. It was also a Sears but was a hand held unit. The circuit board was in the handle and the top was a meter. Looks like when they made that model you had they could not be bothered making up a new board for it. Great video as always Paul.
All of the timing on my race car is done in the ignition box. My Dad and brother have a race pak in their car and we can change the timing during the run. I do have a dwell meter and a timing light in the garage in a box. I should dig in out and give it a go through. Congratulations on 300K Paul!!
Great video! I just bought a vintage Snap-on tach-dwell meter. It needs re-wired, but your video will definitely help if I need to adjust it. Thanks for sharing.
There is no "big thumbs icon" so I will let you know in write I REALLY ENJOY YOUR VIDEOS !!!! thanks a lot for taking the time with this great, educational and quality produced videos!!!
FYI, one would use a dwell meter while cranking the engine, usually with plugs remove, and set the gap while watching the meter. This also avoids getting oil on the point faces since you are not using feelers. Nice vid man
Another fantastic video - very good idea with the second cam for the function-generator! I like your extreme accuracy on the alignment procedures :-) 73s Ernst
I used one of these every day back when I was on the workshop floor, a handy tool, however, given the way old engines wear, everything was an "approximation". As I worked mobile at the owners home, and often had them hovering while I worked, it proved to be a worthwhile tool as most were impressed by the fact I was using "high tech" on their old banger!!
Speaking of Sears Roebuck and Co, some decades ago you could buy from them model T spark coils. We bought one as kids to use for making a Tesla coil. That was around 70 years ago.
Really a great educational video Mr C. on this type gear! I have a lot of Snap On electronic gear from my fathers garage that could use an alinement and refurbishment!
Nice job again Paul, I have a quite large Dwell/Tacho meter in the cupboard for the last probably 30 years since last use, I might drag it out for a play. Someone might be able to use it, thanks 🙂
Hi Paul, Had the same unit. Saw less use when the HEI distributors started making an appearance. Don't know where my unit is now. I sold my shop when I retired in 2018 and closed down my trucking company. Enjoyed the video. You and the family stay safe. 73 WJ3U
Back in the day we used to buy open frame 1mA movements from Farnell (IIRC), and they'd arrive in all sorts of states!.....requiring spindle adjustment top and bottom to keep the coil level as well as adjusting the freeness of the movement. Yes, it was an art to get it all adjusted perfectly and linear.
love the video but i might suggest that a brief description of how the circuit converts hz to meter movement for rpm and duty cycle is converted for dwell
I'll be honest, as much as I love older motors and older electro-mechanical systems, this stuff is why I'd much prefer to drive a vehicle with an electronic ignition haha. Great tutorial though, I'm sure this will come in handy due to my fetish for old automobiles!
Good timing! I use my old Sears unit (later model than this one) but just bought a Heathkit Automotive Scope to test the dwell accuracy thus calibrate - I should have just waited for this video!!
Thanks for sharing. These were used on the old Kettering ignition system. I once got in an argument with the guy at my local tune-up shop. I told him I was looking for a canned answer. He said: you mean "condenser"? No. a canned answer. It's a condenser. But that's beside the points. Let's not dwell on it, OK? I got the canned answer I wanted.
Excellent. I have a Dwell/Tach meter that is much cheaper than this lovely thing and have used it since the 90s. Now I need a function generator to test it! There's always something 😄
I had a Sears VOM back in the early eighties and it was a pretty good meter. Not Simpson quality but plenty good for general use. I don't know if it's still spot on anymore but I'm not surprised your meter came back around with a little tlc.
How ironic that you did this video as I just recently found a really nice Sears unit in someone's trash that does all these tests plus it has all the plug in test cables with it. Unit is in great shape. I'll probably never use it other than maybe the voltmeter and ampmeter. Looks good for the bench though. Also got a near mint complete old g.e. beige plastic portable record player. Can't wait to check it out.
It has other uses believe it or not. It can be used to retrieve codes from OBDI Ford's, and it can be used to place a load test on circuits. Before condemning a purge solenoid, you can put the meter in its place, and it load tests the circuit so that you don't need to do voltage drop tests.
Sigh what memories this brings back. I used several analog meters back in the day for both tach dwell and electrical service in the automotive industry from 1970's to 1990. Now that I am getting into electronics I am sad I sold them in a yard sale and only have digital meters now.
Hi Paul. Many years ago now, I used to be employed as supervisor of a small group of calibrators of mechanical meters. The device should really be calibrated and used in the same way, that is, if it is to be used standing up, it should be calibrated so, or if used lying on its back, then calibrate it in that position. With a good meter, any difference should be very small, but nevertheless when we issued a calibration certificate it would only guarantee the stated accuracy if used the same way it was calibrated.
@@geraldstewart very few mechanical meters will give precisely the same reading in ALL positions. Hence, a tolerance is given, and the instrument is tested in only the positions it is expected to be used. For example, a mechanical AVO meter could be calibrated both vertically and laid on its back. If then used on its side for example, it could be outside tolerance.
I can understand your skepticism working on a Sears branded piece of equipment. It works the opposite way, also. 25 years ago, my cousin handed me a top of the line Carver receiver to repair. I was excited to get my hands on it. It turns out, the receiver was actually made by Pioneer, which was a bit of a let down. I did get it repaired and back to my cousin.
You have to remember that this meter was made during a time when Sears cared about making products well instead of today's habit of making things cheap and customers having to come back to replace it much quicker.
I'm sure that 'Sears' as it existed back in the day, still cares about good products. The problem is that all the people and ethics associated with Sears as it used to be have retired, been pushed out or otherwise replaced with sociopathic greed-mongering hyper-capitalists. It might be money that's the problem, or perhaps it's just unethical folks that just want to use us all to make a quick buck. In many ways life in 2021 is of a much higher quality than in 1960, but our money buys so very little now. I was born in 1990 and even I've seen a drastic down-turn in my 31 years, in the quality of products. We have to bring back more stringent product quality regulations and penalize outsourced production, while incentivizing local production sources.
It has a thin angular circuit board because the same circuit board was used in a smaller handheld version that the circuitry was in the handle and above it was the meter gauge.
I just calibrated a somewhat similar unit to the one in the video (a hand held style) that was also sold by Sears (Made in Japan). It could only read up to ~1000 RPM on the V8 scale even at the highest setting of the calibration potentiometer. I opened it and found a single electrolytic capacitor (47uF/10V) which is laughable since the unit normally run in a 12V-14V environment. I replaced the capacitor with a 47uf/50V and it worked beautifully and calibrated accurately throughout the whole range. Thought of sharing this for anyone who may contemplate such calibration.
Great topic. I have a vintage SUN dwell/tach meter and I just didn't feel like digging in the math to figure out how to simulate pulse train that will simulate engine RPMs or dwell timing. It is pristine except for some slight surface scuff in the paint. Internally it is totally clean. Not sign of any battery corrosion at all ever
Paul, I look forward to learning from your adapter for this dwell/tach meter for it to work with 6V vehicles. Please show enough detail so that I can adopt _that_ to an 8V vehicle (i.e., a 6V Willys that starts a _whole_ lot better on 8V than it does on its original 6V! ;). I've got an "old" Sears dwell/tach test tool that I purchased in the mid-'70s that I'm sure needs a similar calibration like you've shown here.
A great, educational video! Having used dwell-tachs back in the early '70s, I appreciate the quality of this device. So when are we going to see the vintage occupants of Mr. Carlson's garage?
The reason for the wedge shaped circuit board? My guess is that the manufacturer used the same board for the handheld model where the board is mounted in the handle with the meter movement above it.
I had a good feeling that it would align well as soon as I seen the extruded aluminum case, Japan made meter, and brass nut holding the selector knob on. Nowadays I would expect to see an all plastic case, China made meter, and pot metal fasteners. Keep up the great work.
You always impress me. There are times I laugh. You are a very good technician. As a retired Broadcast Engineer who cut my teeth on valve technology, I feel that you are a little bit excessive on the safety of high voltage circuits. It is still better to be safe. On transmitters we ALWAYS did several things. Remove all jewelry. Keep one hand in a pocket. Us the shorting stick to verify the power supply is discharged. Good work! Excellent audio! As always, nice production.
The circuit board shape prob comes from its use in a hand held usage as I am sure one of the big tool brands did a hand held dwell meter with a smaller case but same gauge and function.
Only Mr. Carlson can teach us electronics, optics, radiology, electrical engineering, physics, mathematics, mechanical engineering, and auto mechanics in 1 video and make us enjoy it. (I had to edit...I left out electronics on my comment. Total brain fart)
In the old service station I worked in back in the day, we had a big "SUN" cart with several types of portable meters you could select. The only one I ever saw any mechanic use was the Tach/Dwell meter. I was well worn while all the others looked brand new. It took a lot of punishment. No idea how accurate it actually was. LOL!
![HeathBuilt Voltage Reference Source [Restoration]](http://i.ytimg.com/vi/2LlOGOu8Dlg/mqdefault.jpg)
To learn electronics in a very different and effective way, and gain access to Mr Carlson's personal designs and inventions, visit the Mr Carlson's Lab Patreon page here: www.patreon.com/MrCarlsonsLab
Love your video's Mr C !!
V6s and V8s share the same crankshaft but opposite of each other, so v6=3 and v8=4. What about an in-line 6 cylinder, is that divide by 6 or 3?
@@Daveyk021 on a 4 stroke engine it takes 2 revolutions of the crankshaft to fire all the cylinders. the configuration makes no difference. 3 cylinders fire on a 6 cylinder engine per revolution and 4 on an 8 cylinder.
@@richardcranium5839 Thank you. Also the distributor runs off the crank. I think this morning, I was in lala land thinking the cam shaft. Since a V engine has two, I was thinking that would change the math. I thinker on cars and small engines (when I have time). I need to check the math to test a TAC and DWELL meter I have (it is digital, so it is probably dead nuts on??). I still like the idea of an analog meter for it. I think that is better to watch the needle swing.
I may get on ebay and order and old analog tac/dwell meter before they are all over $1000 after too much of the public see this video.
@@Daveyk021 V engines can also have only one camshaft. They were the older engines that had pushrods and lifters. The camshaft was in the block right over the crankshaft.
I wonder how can someone dislike a video with this level of knowlege and care. Congrats, Mr. Carlson. Your content and you are simply awesome.
Trolls...every channel has them....🙂
@Andrew_koala I think you got it spot on. I don't have the hands-on knowledge on the subject-matters Mr. Carlson shows us (very little practice, I only got the theoretical electromagnetism part of it), but I admire the simplicity and practicality he demonstrates in every video.
Also, I really appreciate the old and new equipment he shows and restores (we never saw 99% of those brands and products in Brazil).
Jealous trolls that will never amount to anything is how dislikes happen. They have nothing better to do but what they do best. Troll
My father had a tach/dwell meter, (which is still (probably) in his garage ;-), that he used to make fine adjustments to the points on his 69 Imperial. They used to call me "Mic Eye" when I was younger cause I could adjust the points without a feeler gauge. (I couldn't really tell the gap, but I had done it so much that I could get it REALLY close, so close that dad rarely had to adjust them once I'd set them) Thanks for the trip back in time Mr Carlson!!! I sure do miss my dad!!!
Thanks for sharing your story Brian!
Just finished fixing up a Canadian made Tuffy Tool model 1813 Tach-Dwell meter , thanks to this video. Having access to a function generator was able to calibrate rpm and dwell accurately. Was out by a bit due to out of tolerance resistors , linearity is perfect across the whole span of the meter. I use this for my Canadian ' 66 Malibu SS . Still running points as the car still has its original 283. Great Job Paul !
For those wondering why 'dwell' matters in old cars with breaker point ignitions: The dwell angle is the number of degrees of crankshaft rotation in which the points are closed. During this period, the magnetic field in the primary winding of the ignition coil is building. When the points open, the magnetic field collapses quickly generating a brief high voltage, which is stepped up even more in the secondary coil eventually arcing across the spark plug gap. The longer the dwell angle (i.e. points closed), the more time there is to build a magnetic field in the primary - an increase in this magnetic fields leads to a higher voltage at breakdown and a better spark.
The dwell angle is set by adjusting the breaker point gap - i.e. how far apart the points are when they're pushed open by the cam lobe. A larger gap implies a smaller dwell (inverse relationship) because the breaker points in the small dwell case are adjusted such that they open sooner on the cam lobe and are ultimately pushed farther apart at the top of the lobe.
Because breaker points can be pitted due to arcing, adjusting the points gap distance (with feeler gauges) is relatively inaccurate (as the points faces may not be flat) and having a dwell meter does a much better job at getting a proper adjustment. Incidentally, I believe vintage race cars occasionally used dual point systems (and possibly additional coils ?) to maximize coil charging at high rpms - a scheme where every other ignition cycle would take place on the alternate coil/points set that would be fully charging during the previous cycle. I may have the details of this last part wrong. Anyway, I hope this is interesting/helpful to someone out there :-)
Very well said!
The ignition dwell angle isn't derived from crankshaft rotation. It's is derived from distributor rotation. Crank rotates twice the speed of the cam. For example a 4 banger has breaker lobes that are 90 degrees apart, so the dwell angle would be around 45 degrees.
@@MrCarlsonsLab No points in todays cars ???
Thanks for the explanation because I was wondering about dwell angle!
@@dak682 More modern vehicles will have gone to electronic ignition, which usually uses the car's onboard computer to measure the RPM directly, and then decide when to fire. As long as it's working correctly, it's got less moving parts to deal with and less calibration needed, as well as allowing for variable ignition timing through all RPM bands and air temperature conditions with more advanced vehicles. The biggest downside is that especially in 2021 cars, nothing is really user/owner-serviceable any more.
This is all new to me and I've driven lots of old cars. I'm off to a new video to fill that gap. Need to learn about dwell. I never fail to learn something new from these videos.
Glad it was helpful!
This brought me back to the 80s watching the technician calibrate our Allen Test scope. Great explanation.
When I started doing mechanic work over 50 years ago that was the tool to have to get your car is running great. I really enjoyed this video. It’s because of videos like this that I became a patron sometime ago. The only thing I can use my old dwell tachometer on is the tractor.🤣👍 I look forward to all your videos. Keep safe Paul.
Thanks 👍
My old man taught me this, on a Craftsman in the late 70's early 80's..He's missed. Thanks for this
Glad you enjoyed Charles!
This video was on the mark as I just purchased an almost identical Sears meter with an additional range for voltage. The meter needs calibrating so your video was just the help I needed. Thanks so much Mr Carlson.
Impressed is somewhat miss-understated, I really did not expect this 'Pro'! meter to be anywhere near as accurate, (so much is labelled 'Pro' now days and it means crap really) hats off to the designer and manufacturer, they really came up with something quite special, obviously the meter movement is of quite high quality not something you would get today unless you pay 'think of a number and double it' price, the old school stuff wins again, thanks very much for showing this Paul it was VERY interesting to watch and see it truly shine at the end!
Thanks for your kind comment Keith, and taking the time to write too!
My lifetime career was in electronics! 3 years at Westinghouse, 18 at Kodak and 12 at Rochester Institute of Technology! Loved my life’s work! Over those years I collected dumpster dive test instruments bound for the recycler! Most need repairs!! Want to fix them! Ha ha! Thanks for the videos!
Glad you enjoyed Bob!
@@MrCarlsonsLab I have a 67 Mustang and 72 VW beetle and I still have my old Dixco tach/dwell meter to adjust ignition timing! Now I know how to calibrate it! THX!
I’m also restoring a C64 and disc drive, fixing some old cb radios and building cb antennas! I’ve been retired 8 years but I try to learn something new every day! Thanks for that!!!
Knowing that you have moved the labs all around, it feels a little funny to see the old main lab in the intro and outro! Sears always had major manufacturers make their house brand devices. It is possible that the design really is a SUN product though it really does not matter. Nice job as is your normal! Even my "old" truck (1973) has electronic ignition so the dwell function to me is not needed. So many people today look down on the old way to do things. A needle is much easier to use when doing things like setting RPM as it is the way our brain works, analog not digital. Great job on a device I had totally forgotten about! NOW TO THE UFO device!!! :D
Thanks Paul,still have 3 old dwell tach meters that need servicing,when points rubbing blocks went from fibre to plastic you really had to stay on top of dwell angle and that little capsule of grease was ever important,changed quite a few breaker plates on old fords as the dwell changed quite a lot on them,amazing how much better they ran with steady dwell
Wow ,I haven't opened a Sears Dwell meter , I didn't realize how much adjustment was avalible,Great video,
Ive been looking for how to do this for ages. I have 2 of these. One is accurate and the other not and I didn't know how to fix it. I'm impressed with how easy this is to do. Thanks.
You are welcome!
Hi Paul. You have just made lot's of shade-tree mechanic's and hometown racing team's Very Happy !!!
Thanks for the video.
Sears tune up equipment was always very accurate OoB. I owned several over the years. In the 60's, the name they were sold under was Penske, as in Penske Racing
Working on small sports cars, the most important readings were usually for low idle speeds. High speeds were not used as much, except for maybe checking your tachometer.
The dwell meter was especially useful as that was the function that indicated the quality of your distributor bearings and points-springs.
I was kind of hoping you were going to have to build in some calibration controls if this didn't have any originally. Please set aside some time in the future, to do one of those too.
Thanks again.
This video is a very nice contribution to the automotive world; it will be a resource for decades. Thanks.
Yet another great video and Paul your knowledge knows no bounds !!
Thanks 👍
That is the cleanest dwell meter I've ever seen in my life lol didn't know it can go out of spec sitting in a box.
I was going to congratulate you on 300k subscribers last week and didn't get around to it. So, congratulations on 301k subscribers! Thanks for your great videos!
I love Mr Carlson's Lab!
Learned a few things on this video. Strangely not about electronics but motors!
This is unique, always surprised by how your acumen in electronics applies to so many different fields.
Thanks for your kind comment Jim!
Thanks Paul! Got out my old ArcherKit Engine Analyzer to check the calibration and sure enough it was off! That kit had you do the CAL of the tach using a line cord with a few 56K resistors in series with the Hot and Neutral. You plug it in the wall socket and attach your test leads to the ends of the resistors to get 60Hz (ish) line frequency. Got you close, thanks for the video and math to check the other RPMs!
Glad it helped Mike!
Thanks Paul for what you do here and on Patreon!
You're very welcome Robert!
Always excited to watch another video of you!
I like restoration of old Devices in your lab
Thanks!
Paul, As smart as you are I have to wonder if there is anyone that you look up to. Before I get any older I'd better start your electronics classes very soon! Thank you a thousand times over!
Had one in the early 80's with the wedge shaped circuit board. It was also a Sears but was a hand held unit. The circuit board was in the handle and the top was a meter. Looks like when they made that model you had they could not be bothered making up a new board for it. Great video as always Paul.
Thanks for stopping by Buddy!
Congrats on the 300k! Very much deserved. Best electronics channel in "RUclips town"
Thanks Daniel!
I think the last time I used one of these was probably 1983 and yes, it was from Sears! That and the stroboscopic timing light. Fun times.
All of the timing on my race car is done in the ignition box. My Dad and brother have a race pak in their car and we can change the timing during the run. I do have a dwell meter and a timing light in the garage in a box. I should dig in out and give it a go through. Congratulations on 300K Paul!!
Great video! I just bought a vintage Snap-on tach-dwell meter. It needs re-wired, but your video will definitely help if I need to adjust it. Thanks for sharing.
Glad to help Frank!
Great video! Once again I learned a lot from your videos. Thanks, Mr. Carlson!
Thanks for the feedback Robert!
There is no "big thumbs icon" so I will let you know in write I REALLY ENJOY YOUR VIDEOS !!!! thanks a lot for taking the time with this great, educational and quality produced videos!!!
Thanks for your kind words Edgar!
I have an old, different Sears Tach-Dwell meter too. I think I'll be doing this now. Thank You!
Glad it helped Bill.
FYI, one would use a dwell meter while cranking the engine, usually with plugs remove, and set the gap while watching the meter. This also avoids getting oil on the point faces since you are not using feelers. Nice vid man
Very interesting and a very good video, Paul; much enjoyed.
Glad you enjoyed it!
Another fantastic video - very good idea with the second cam for the function-generator! I like your extreme accuracy on the alignment procedures :-) 73s Ernst
I used one of these every day back when I was on the workshop floor, a handy tool, however, given the way old engines wear, everything was an "approximation". As I worked mobile at the owners home, and often had them hovering while I worked, it proved to be a worthwhile tool as most were impressed by the fact I was using "high tech" on their old banger!!
Thanks mr. Carlson. Interesting as always. That studio mike is a gem, excellent sound quality too. I'd love to see the electronics of that.
Speaking of Sears Roebuck and Co, some decades ago you could buy from them model T spark coils. We bought one as kids to use for making a Tesla coil. That was around 70 years ago.
Really a great educational video Mr C. on this type gear! I have a lot of Snap On electronic gear from my fathers garage that could use an alinement and refurbishment!
Glad it was helpful!
Nice job. Good to stray out of radios and such. Maybe work on a cool old timing light next?
Nice job again Paul, I have a quite large Dwell/Tacho meter in the cupboard for the last probably 30 years since last use, I might drag it out for a play. Someone might be able to use it, thanks 🙂
Glad you enjoyed Dave!
Always learn so much from your vids ....thanks again !!!
Sir you are a man of many talents.
Excellent video! I am really looking forward to the analog instrument movement.
Hi Paul,
Had the same unit. Saw less use when the HEI distributors started making an appearance. Don't know where my unit is now. I sold my shop when I retired in 2018 and closed down my trucking company. Enjoyed the video. You and the family stay safe. 73 WJ3U
Back in the day we used to buy open frame 1mA movements from Farnell (IIRC), and they'd arrive in all sorts of states!.....requiring spindle adjustment top and bottom to keep the coil level as well as adjusting the freeness of the movement. Yes, it was an art to get it all adjusted perfectly and linear.
love the video but i might suggest that a brief description of how the circuit converts hz to meter movement for rpm and duty cycle is converted for dwell
Great video, thanks for sharing!
I'll be honest, as much as I love older motors and older electro-mechanical systems, this stuff is why I'd much prefer to drive a vehicle with an electronic ignition haha. Great tutorial though, I'm sure this will come in handy due to my fetish for old automobiles!
Good timing! I use my old Sears unit (later model than this one) but just bought a Heathkit Automotive Scope to test the dwell accuracy thus calibrate - I should have just waited for this video!!
You Or Genius Sir Very Detail Explain & nice Video Sir.
Excellent Video as always! Glad to see you are getting things close, so you can start making videos on restorations!
In the day, I always wanted one. Now I have one for my 68 Karmann Ghia, Now that I know; I should align it. Thank you!
Glad it helped David!
I learned smth new again 😊👍 TY Paul!
That was a good one. Haven't seen one of those in years. Keep up the good work
Thanks for sharing. These were used on the old Kettering ignition system. I once got in an argument with the guy at my local tune-up shop.
I told him I was looking for a canned answer.
He said: you mean "condenser"?
No. a canned answer.
It's a condenser.
But that's beside the points.
Let's not dwell on it, OK?
I got the canned answer I wanted.
Excellent. I have a Dwell/Tach meter that is much cheaper than this lovely thing and have used it since the 90s. Now I need a function generator to test it! There's always something 😄
Great video. Thanks.. The wedge shaped PCB is probably because the same board was used in a hand-held device variety of the same meter. Just a guess..
You're probably right!
I had a Sears VOM back in the early eighties and it was a pretty good meter. Not Simpson quality but plenty good for general use. I don't know if it's still spot on anymore but I'm not surprised your meter came back around with a little tlc.
Very nice avatar Deacon Blue! I love my Simpson too. BTW: My SG membership card labels me as a "Healer of Appliances".
Bravo!
I’d love to have a dwell. Great video.
How ironic that you did this video as I just recently found a really nice Sears unit in someone's trash that does all these tests plus it has all the plug in test cables with it. Unit is in great shape. I'll probably never use it other than maybe the voltmeter and ampmeter. Looks good for the bench though. Also got a near mint complete old g.e. beige plastic portable record player. Can't wait to check it out.
It has other uses believe it or not. It can be used to retrieve codes from OBDI Ford's, and it can be used to place a load test on circuits. Before condemning a purge solenoid, you can put the meter in its place, and it load tests the circuit so that you don't need to do voltage drop tests.
Sigh what memories this brings back. I used several analog meters back in the day for both tach dwell and electrical service in the automotive industry from 1970's to 1990. Now that I am getting into electronics I am sad I sold them in a yard sale and only have digital meters now.
Super fun. Thanks Mr. C. It is appreciated.
really enjoyed this video...
Glad you enjoyed it Ron!
Very interesting video.
So sad the old lab is gone. All the great memories 😢
It's just going to get better :^)
Hi Paul. Many years ago now, I used to be employed as supervisor of a small group of calibrators of mechanical meters. The device should really be calibrated and used in the same way, that is, if it is to be used standing up, it should be calibrated so, or if used lying on its back, then calibrate it in that position. With a good meter, any difference should be very small, but nevertheless when we issued a calibration certificate it would only guarantee the stated accuracy if used the same way it was calibrated.
You need to adjust the meter movement so it works right in all positions
@@geraldstewart very few mechanical meters will give precisely the same reading in ALL positions. Hence, a tolerance is given, and the instrument is tested in only the positions it is expected to be used. For example, a mechanical AVO meter could be calibrated both vertically and laid on its back. If then used on its side for example, it could be outside tolerance.
I can understand your skepticism working on a Sears branded piece of equipment. It works the opposite way, also. 25 years ago, my cousin handed me a top of the line Carver receiver to repair. I was excited to get my hands on it. It turns out, the receiver was actually made by Pioneer, which was a bit of a let down. I did get it repaired and back to my cousin.
"Is that a REAL poncho or a SEARS poncho" - Frank Zappa :)
You have to remember that this meter was made during a time when Sears cared about making products well instead of today's habit of making things cheap and customers having to come back to replace it much quicker.
Absolutely!
I'm sure that 'Sears' as it existed back in the day, still cares about good products. The problem is that all the people and ethics associated with Sears as it used to be have retired, been pushed out or otherwise replaced with sociopathic greed-mongering hyper-capitalists. It might be money that's the problem, or perhaps it's just unethical folks that just want to use us all to make a quick buck. In many ways life in 2021 is of a much higher quality than in 1960, but our money buys so very little now. I was born in 1990 and even I've seen a drastic down-turn in my 31 years, in the quality of products. We have to bring back more stringent product quality regulations and penalize outsourced production, while incentivizing local production sources.
Great little video on the tach/dwell. Now please straighten the meter ( grin. )
Hi Mr C!
Good job 👍
Hey, thanks!
It might be interesting to also have the complimentary video: How to Tune an Engine with an Oscilloscope. : )
It has a thin angular circuit board because the same circuit board was used in a smaller handheld version that the circuitry was in the handle and above it was the meter gauge.
I just calibrated a somewhat similar unit to the one in the video (a hand held style) that was also sold by Sears (Made in Japan). It could only read up to ~1000 RPM on the V8 scale even at the highest setting of the calibration potentiometer. I opened it and found a single electrolytic capacitor (47uF/10V) which is laughable since the unit normally run in a 12V-14V environment. I replaced the capacitor with a 47uf/50V and it worked beautifully and calibrated accurately throughout the whole range. Thought of sharing this for anyone who may contemplate such calibration.
Great topic. I have a vintage SUN dwell/tach meter and I just didn't feel like digging in the math to figure out how to simulate pulse train that will simulate engine RPMs or dwell timing. It is pristine except for some slight surface scuff in the paint. Internally it is totally clean. Not sign of any battery corrosion at all ever
Paul, I look forward to learning from your adapter for this dwell/tach meter for it to work with 6V vehicles. Please show enough detail so that I can adopt _that_ to an 8V vehicle (i.e., a 6V Willys that starts a _whole_ lot better on 8V than it does on its original 6V! ;). I've got an "old" Sears dwell/tach test tool that I purchased in the mid-'70s that I'm sure needs a similar calibration like you've shown here.
Will do Bob. Should be an easy circuit.
awesome!
A great, educational video! Having used dwell-tachs back in the early '70s, I appreciate the quality of this device. So when are we going to see the vintage occupants of Mr. Carlson's garage?
Always interesting and fascinating content 🙂👍
Glad you enjoyed it!
I liked this Vid I Have a Sears Tack/Dwell meter it is a dual meter it also has a ohm/volts meter
The reason for the wedge shaped circuit board? My guess is that the manufacturer used the same board for the handheld model where the board is mounted in the handle with the meter movement above it.
You are probably correct.
that subtle sears shade.
This is like apprenticing to Gandalf. All the old knowledge, spells, but most importantly, wisdom. You cannot buy this anywhere.
I had a good feeling that it would align well as soon as I seen the extruded aluminum case, Japan made meter, and brass nut holding the selector knob on. Nowadays I would expect to see an all plastic case, China made meter, and pot metal fasteners. Keep up the great work.
You always impress me. There are times I laugh. You are a very good technician. As a retired Broadcast Engineer who cut my teeth on valve technology, I feel that you are a little bit excessive on the safety of high voltage circuits. It is still better to be safe. On transmitters we ALWAYS did several things. Remove all jewelry. Keep one hand in a pocket. Us the shorting stick to verify the power supply is discharged. Good work! Excellent audio! As always, nice production.
The main thing here is that he has to be careful about safety warnings because he doesn't want to get into trouble if someone does something silly.
very cool meter - and really nicely described. Now... will you do a reverse of the circuit?
The circuit board shape prob comes from its use in a hand held usage as I am sure one of the big tool brands did a hand held dwell meter with a smaller case but same gauge and function.
10:25 - That look like gain-inaccuracy as opposed to linearity; the error increases with frequency.
I rebuilt my serious exhaust gas analyzer and got It working flawlessly once again
Only Mr. Carlson can teach us electronics, optics, radiology, electrical engineering, physics, mathematics, mechanical engineering, and auto mechanics in 1 video and make us enjoy it. (I had to edit...I left out electronics on my comment. Total brain fart)
In the old service station I worked in back in the day, we had a big "SUN" cart with several types of portable meters you could select. The only one I ever saw any mechanic use was the Tach/Dwell meter. I was well worn while all the others looked brand new. It took a lot of punishment. No idea how accurate it actually was. LOL!
Great video interesting
I have a Hawk hand held dwell tach meter and the casing is exactly the same shape as that circuit board so, mystery solved.
Nice catch !....cheers.
I was just going to post the same.
Now we know who made it for Sears
Nice video, does the square wave swing from positive to negative or just positive to zero volts? thanks.
It's goes from zero to positive, no polarity change.