One thing I realised with my own programmable DC load project is to never under estimate the resistance of crocodile clips+cable. They can very easily account of 1 ohm or more. Charging or discharging at around 1 Amp explains the huge voltage drop.
I would very very recommend a hot air station for SMD soldering. It changed everything for me. You just flux the pads, put on a small blob of solder paste on each pad, plop your component in place and heat everything up with the hot air. The way the solder melts and pulls the component in place with fluid tension is magical to watch.
I have a soldering iron very similar (if not identical to that one). The first thing I had to do was take it apart, to fix the earth continuity for the iron tip due to a dry joint on the iron connector at the PCB (looks like mine is designed for wires, not PCB mounting). While I was in there, I changed the mains lead for a silicone one without a sleeved earth pin...
Some one suggested a good idea. To disable adblock during the night, and play a long playlist. I think I'll do that tonight on one of your playlists. I'll leave my computer on, but turn off my monitor. I like your channel, and I want you to make lots and lots of Google's money. Better you than them :)
Hi Julian, the 2.5V protection boards, are more of and anlogue current shunt, that starts at a low current and increases. The big tranistor is a NPN and has about 1V Vsat so gets hot. The 2.7V clamps might have a Mosfet but at 2.5V it is hard to switch Amps at that the lower gate voltage. With the Vsat you will never enough voltage to light a LED. Yes removing some shunt resistors would help but reduce the protection.
Hello Julian! 👍 That's very nice of Adam Welch, that he has given you a soldering station! Not only did I subscribe to you, but also Adam Welch's channel - very interesting! Best regards from Austria! PS .: Yes, I know that this video is from August 2017, but I'm watching all 88 videos from your playlist!
LOL The drop across the diode gets higher when the forward current is higher, I find it funny when people think it's gonna be the same. You can expect 0.6v or more across the shottky when you're passing rated current through it.
The circuit works just fine. First of, the voltage drop across those test leads plays a large part in you measurements. And secondly, the circuit is linear and not just switching on and of. The fact the the current starts to rise slowly as you go over the protection voltage should tell you that. (19:40 in the video). The circuit is just dissipating enough power to keep the voltage at the terminal @ 2.5 Volt.
It's a lot easier if you pre-tin the (scraped-off) pads first, then use a desoldering iron or solder wick to suck up the blobs. Now it's super easy to solder the SMD LEDs on without overheating them! Cheerios!:)
Hey Julian - Your cables are crap - this explaines everything about the malfunction and odd behavior of the protectioncurcuits, multimeter and power supply.
But not when there's over 1V of drop, you don't. Just buy some croc clips and proper think copper wire (speaker wire or old mains flex is good) to make your own.
Julian Ilett Hi Julian I haven't watched all your video yet just paused it to message you 1st I hear you mention about 3 tenths of a volt drop with the diode I seem to remember from Tech College days in late 70s Silicone is usually 0.7volts drop and Germanium 0.3v so 1v overall is not far off being spot on...So don't forget to up the supply voltage by about 1.2v so the super cap can then charge ok and your strange things will stop lol. ...I remember i once fitted a large security system with 64 Camera's connected upto DVR,s and had a couple of Cams that kept breaking up took ages too twig it was all volt drop on the cables so I adjusted the PSU to give 18v and that solved all the problems everything connected to the psu had there own 12v regs and as long as 13.8v or more was seen at the other end of the cable run everything worked😊 that was about 20yrs ago and I was never called back for any problems....Enjoy the soldering station and thumbs up 👍to Adam for fixing you up with it. ..
Julian please look at some SMD soldering tutorial you need that urgent. I can give you a tip right away: Start to put solder on one pad first, then solder the led on that one, by reheating the solder. You have one free hand now so you can hold the LED down (use a tweezers) and finish solder the last end of the LED by now adding solder to the last pad.
The LM431 is an analog device; it won't "trigger" at a specific voltage. In this circuit, it's functioning as a linear voltage regulator, biasing the gate of the MOSFET at its zener voltage. That's nominally 2.5V, but there's a tolerance of as much as +/-2.2%, depending on which part you buy.
How do Julian. Your Blue LED has 0.4 Ohms shunted across it and like you calculated, you would need to be pushing 6.25 Amps through those resistors to get 2.5V to develop across the LED. I'm assuming the LED voltage is closer to 3V? which Ohms Law will tell you, would require 7.5 Amps. Your Supply Voltage is already less than 3V so the LED is never going to light with those values. Intended as friendly help, not a critisism. Thanks for the Videos!
Biggest question is: what is the rds on of the mosfet? If it is equal as the three resistors (at best @2.5V gate) then you only have halve the voltage on the led. Don't think a blue led likes 1.25V. My guess is that the rds on is much higher.
Julian, im pretty sure its not a mosfet on the supercap protection boards, its a BJT and forms together with lm431 a linear regulator. So no chance to lightup a blue LED. They are not digital on/off with a hysteresis. And 6.25A they suppose to never reach that much current. I guess these protection boards are limited around
I like the mention of a supercapacitor lighting project, how about a solar garden light with a big capacitor rather than a battery, i think that would make for an interesting project.
What's the temperature rating of a supercap? That might be a problem - and it wouldn't half need a big box, (unless you could find a long thin capacitor that could hide in the stem)
you got the same soldering iron as me except mine says a different brand :):) its really good I love my soldering iron I got it for my birthday last year. one thing tho the temperature needed calabrating when I got it it was way hotter than it said on the display like 45 degrees more or smth so maybe check yours too. once I set it tho its been fine since
The mosfet is being used in the linear region as a variable resistor and not turning all the way on. Recall that the gate must be more positive than the drain by the "Vt."
you could have used your multimeter to measure the voltage drop over the diode and each of the cables separately... with only 2.5-ish volts as gate voltage it is not surprising that the MOSFET is not fully turned on. Actually a bipolar transistor would have done a much better job here...
If you're going to do any SMD soldering, you should invest in some fine-tip tweezers. I have a pair of Aven tweezers that cost me about $4, but they can probably be had for less.
I actually ordered a set of "7Pcs Anti-Static Tool Plastic Tweezer Heat Resistant" that have some nice tips on them. I got them for this type of work and for desoldering old boards. Costs about $2 from ebay seller wikita.
In my experience amplifiers catch fire mostly because the bias voltage divider resistance is too low. It can also be caused by having the input voltage too high on the primary or secondary stage which can overdrive the FETs causing clipping. If I had more information about the setup of your amplifiers I could probably tell you more as I've built quite a few myself and had to deal with such problems.
Just a minor nitpick about the heat dissipation of those resistors. 2.5/0.4 gets you the amps, but the important figure in resistor heat dissipation is the watts. Those poor little sods are dissipating 15.625 watts!
A 700 farad capacitor charged to 2.5 volts is going to contain about 1700 coulombs when fully charged. If you are charging it with 500 mA, it is going to take about 3400 seconds, which is almost an hour, to charge it up. So really, it isn't surprising that the voltage increases very very slowly.
I have that exact soldering iron and straight away i recommend you cut the plug off as it has a shielded earth pin aswell as use a temperature between 330 and 370
I was thinking the same thing when he was doing a little probing. Find out how much voltage before the diode, after the diode, and at the cap (which he already knew). I was wondering if the power supply was misreading something and giving the wrong value since it can't sense the voltage coming from the cap.
Did you double-check that both of the LED connections are actually connected to the board? Could be a bad solder joint, meaning the LED isn't really connected.
Get some rosin flux, either a pen or liquid, apply a drop to the parts before soldering, works wonders. Have a look at Mr. Carlson's Lab channel for some good soldering advice.
I tried to do this last month and ran into the same issue. All of the voltage drop was taking place across the mosfets and got vary hot. One thing I did notice water the current through the mosfet would rise with the voltage. I didn't think about taking off one of the resistors that sounds like a great idea I'm going to have to try that.
Those china cables have 1 Ohm. Throw them away. Had the same ones and got quite the same issues. Since then I solder my own crocodile cables with 2,5² or 4² for low Volate experiments.
Yep, I agree. I'm going to redo my cables as well. I saw a video that showed the resistance before and after, and it was substantial. I just need to get the banana clips ordered.
Actually it seems to be working fine. What is the point where it draws no current vs where it starts drawing "some" current. It may be a progressive limiter.
Julian you know the panel that is mounted on the neck of a colour CRT would have three class A amps one for each colour you know R,G,B could you not use that sort of thing and possibly use the third class A amp for the base so Left,Right and Base but it would be a good idea to remove common transistor TR5 which seems to connect the emitters of the class A amps to ground through a current sink, just an Idea.
Julian, that's not how you solder. You should have tinned the exposed copper on the board first. That way you could have just heated each pad to melt the solder on both the pad and the LED.
The crocodile clip cables are rubbish. I ordered some, not from china and there is barely any copper inside... Gonna replace them with my thick braided red wire I have around, very flexible stuff. Very nice wire. The clip plastic color is enough for me.
Are the cheap supercapacitors largely factory rejects and pullouts or what? I see a lot of people finding several in a batch defective or "weak" and sometimes arriving with blobs left over from obvious desoldering.
I thought "never gonna work", as the LED is across a very low resistance - and will a blue even turn on at 2.5V anyway? And the lead resistance evident on charging is also messing up the voltage reading of the PSU. so for a point before it current limits, you actually have a shunt regulator vs the lead resistance. Just how much power can a dinky surface mount transistor and some tiny resistors dissipate ?
Hi, i like your video's Julian. Do you have a link for the small power regulated supply you used to charge those supercaps ? Thanks. Sorry, found it ...;-)
Sir, Its a nice video. I brought the balancing board. I tried testing the balancing board for verifying its regulation by connecting the supercapacitor and a variable power supply to the same slot and used a multimeter to measure the voltage of the supercapacitor. Not sure if the method is right because the multimeter would not be able to show the actual voltage of super cap as the source is also connected to same point. By this method, I find the voltage rising above 2.8V. Didnt check after that. Is there any way to ascertain that regulation is happening? What is the max applicable voltage to the board for the regulation to happen?
Hi Julian, might I inquire as to the time it takes for the better percentage of your Ebay orders to arrive in the post please :-) I am waiting on some items, solder being one urgent item, that are pushing the 70 day mark currently!! Interested to know the shipping times for EU and GB
When you last used these SC voltage protectors you used a digital version with a voltage checking chip, the ones in this video are analogue using a precision 3 terminal zener to drive an analogue device, I know, I used similar last year and tried your LED idea, it didnt work...
I don't understand why you are so timid when it comes to the current setting you're using to charge those capacitors... Here's a thought: How about instead of an LED, connect the input side of an optoisolator across those resistors. Then you can do all sorts of things with the output sides, and it won't depend so much on the exact details of the circuit you're trying to monitor.
hi julian can i ask you a question please it is can i run 2 x 5mm led in series from one pin in an arduins as i want to make traffis lights for a model railway for a cross road junction i have seen sone done on youtube but it does not make it very clear as to how they are done i know that i will need a resistor but i am worried that the 2 led lighting together will damage the arduino thanks james
james o'connell - An arduino's digital pins can handle 2 leds in series just fine. Just be sure to add thir forward voltages when you calculate the resistor value
hi benjamin thanks for your help so i would need 1 resistor for each led and the resistor must be for 5 volts power is this correct again thank you for your help regards james
John Armstrong The voltage drop depends on current flowing through the device, check the datasheet. See the graph named instantaneous forward voltage vs instantaneous forward current.
MrJohhhnnnyyy Ah! Does the voltage drop increase or decrease with current? I was using one of these ebay round 10a ones as a blocker on my solar system and the voltage drop was 0.6v and it got very hot at 5a but it was sold as a schottky. When I changed it for a huge true flat twin Schottky diode out of a pc power supply (using only one side) the voltage drop is only 0.3v and it doesn't get particularly hot?
The voltage drop rises with current. Diodes in that "small" package you refer to have a rating of 5A maximum, usually. So having a 0.6V drop at full current is pretty damn good. The small diode dissipated 0.6V*5A=3W that's why it got hot, the TO-220 package one dissipated only 1.5W. That package can stay reasonably cool at this dissipation level without any heatsink.
MrJohhhnnnyyy I really do appreciate your reply. I have so much to learn and I am enjoying my new hobby. I hope that folks like you will continue to tolerate stupid comments.😄
It's alright, you can't know everything. We all started from zero sometime ago, it just takes time to learn all these tricks. I just found it funny that Julian sounded so confused about it, 'cause he has much experience. He is pretty good at digital stuff, though. Like micro's, logic chips, those Z80's :D I know about diodes and simple analog circuits, but when it comes to micro's and those old processors, I know bugger all :D
That's my issue, I have several multimeter's They all say something different. I can't trust them. My Fluke killed my 18650's because I had it set to 4.15v and it overvolted 4.3v... I figured it couldn't be off that much, but it was... My $25 multimeter is more accurate than my Fluke for low voltage
7 лет назад
got a 2 k ohm and 1 k ohm resister an 17 volts in and trying to get 9v out with voltage divider and it dosnt work dno wt to do lol
Learn how to calculate the values for a potential divider. Or cheat: www.electronics2000.co.uk/calc/potential-divider-calculator.php You are never going to get 9V with those values.
Perhaps it's finally time to do a video on learning how to solder (flux etc) you may find it amusing that we all moan about it, but you have so many subscribers that if you learned then many of them would to...
I'm curious as to why you need the diode in the first place, except to protect against accidental reverse-bias the 1st time. I'd just try some short lengths of 14-16 ga. wire direct from the power supply to the cap to minimize the voltage drop across the connecting leads. Then measure the voltage drops. I don't see how you could get more than .8 volts across the diode without letting the magic smoke out.
f ridge yeah I could just shove in a chip like 4060 but I don't want to use frequency dividers for it. I want to make it very minimalist. Plus it's not novel. As you said, it's very common.
my conclusion, despite you´re needing much more diameter on your cables, these shitty overvoltage protection circuits are the most crappy and dangerous things i came across so far... Just take a look at the board itself..there is a voltage drop sensor which acts as a Zdiode, but how sharp is its knee when it conducts? The temperature on that MOSFet is an nice indicator, that there is something fundamental wrong here, as i thing that the output of the overvoltage detetcor isn´t able to drive the mosfet into saturation, thus leaving it somewhere within its linear region, make it dissipating the power instead of sending it straight into these resistors. Bring your scope to the bench and probe the mosfet gate voltage, and check its datasheet, would be a nice idea..;) You should really never ever trust these china crap, but test them prior throughout. it´s better being save than sorry, and an exploding superCap is not what you want to ever experience...usually it´ll catch fire and you´ll also have a "wonderful" blowoff as well... Nice video as always...keep ´em comming :)
Im glad the soldering iron seems to work well. A small token for thanks for the numerous frankly brilliant videos that I've enjoyed over the years.
Thank you kindly :)
Adam's channel is great as well. I just wish I had a garden so I could go solar........... (sigh)
Nick B Although his desulphater thingy has yet to revive my knackered breakers yard car battery pack!😄
Do you have a link where you bought it? It looks very good and I'm searching a new iron right now.
Hey Adam, Any chance of sending me one of these soldering irons too? :O)
I have subscribed to your channel....
"...they always seemed to catch fire, my audio amplifiers.."
Yet, we still subscibe.
Brilliant.
One thing I realised with my own programmable DC load project is to never under estimate the resistance of crocodile clips+cable. They can very easily account of 1 ohm or more. Charging or discharging at around 1 Amp explains the huge voltage drop.
I would very very recommend a hot air station for SMD soldering. It changed everything for me.
You just flux the pads, put on a small blob of solder paste on each pad, plop your component in place and heat everything up with the hot air. The way the solder melts and pulls the component in place with fluid tension is magical to watch.
I have a soldering iron very similar (if not identical to that one).
The first thing I had to do was take it apart, to fix the earth continuity for the iron tip due to a dry joint on the iron connector at the PCB (looks like mine is designed for wires, not PCB mounting).
While I was in there, I changed the mains lead for a silicone one without a sleeved earth pin...
Some one suggested a good idea. To disable adblock during the night, and play a long playlist. I think I'll do that tonight on one of your playlists. I'll leave my computer on, but turn off my monitor. I like your channel, and I want you to make lots and lots of Google's money. Better you than them :)
Hi Julian, the 2.5V protection boards, are more of and anlogue current shunt, that starts at a low current and increases. The big tranistor is a NPN and has about 1V Vsat so gets hot. The 2.7V clamps might have a Mosfet but at 2.5V it is hard to switch Amps at that the lower gate voltage. With the Vsat you will never enough voltage to light a LED. Yes removing some shunt resistors would help but reduce the protection.
+Graham Wise Yes, I've since noticed it's not a MOSFET :/
+Graham Wise I'll take a closer look at this circuit in due course :)
I finally bought two of that buck converter you use so much to power various projects because it looks so useful. Thanks for another great video
now that is nice of Adam to send you a soldering station !
Hello Julian! 👍
That's very nice of Adam Welch, that he has given you a soldering station!
Not only did I subscribe to you, but also Adam Welch's channel - very interesting!
Best regards from Austria!
PS .: Yes, I know that this video is from August 2017, but I'm watching all 88 videos from your playlist!
LOL The drop across the diode gets higher when the forward current is higher, I find it funny when people think it's gonna be the same. You can expect 0.6v or more across the shottky when you're passing rated current through it.
The circuit works just fine. First of, the voltage drop across those test leads plays a large part in you measurements. And secondly, the circuit is linear and not just switching on and of. The fact the the current starts to rise slowly as you go over the protection voltage should tell you that. (19:40 in the video). The circuit is just dissipating enough power to keep the voltage at the terminal @ 2.5 Volt.
I suggest getting a genuine hakko tip for the new iron. They work much better than the China ones.
It's a lot easier if you pre-tin the (scraped-off) pads first, then use a desoldering iron or solder wick to suck up the blobs. Now it's super easy to solder the SMD LEDs on without overheating them! Cheerios!:)
Hey Julian - Your cables are crap - this explaines everything about the malfunction and odd behavior of the protectioncurcuits, multimeter and power supply.
I love el-cheapo :)
But not when there's over 1V of drop, you don't. Just buy some croc clips and proper think copper wire (speaker wire or old mains flex is good) to make your own.
Julian Ilett Hi Julian I haven't watched all your video yet just paused it to message you 1st I hear you mention about 3 tenths of a volt drop with the diode I seem to remember from Tech College days in late 70s Silicone is usually 0.7volts drop and Germanium 0.3v so 1v overall is not far off being spot on...So don't forget to up the supply voltage by about 1.2v so the super cap can then charge ok and your strange things will stop lol. ...I remember i once fitted a large security system with 64 Camera's connected upto DVR,s and had a couple of Cams that kept breaking up took ages too twig it was all volt drop on the cables so I adjusted the PSU to give 18v and that solved all the problems everything connected to the psu had there own 12v regs and as long as 13.8v or more was seen at the other end of the cable run everything worked😊 that was about 20yrs ago and I was never called back for any problems....Enjoy the soldering station and thumbs up 👍to Adam for fixing you up with it. ..
back to video ☺☺☺
OMG - I missed a letter! call the cops! Here's some letters for you: S T F U
Julian please look at some SMD soldering tutorial you need that urgent. I can give you a tip right away: Start to put solder on one pad first, then solder the led on that one, by reheating the solder. You have one free hand now so you can hold the LED down (use a tweezers) and finish solder the last end of the LED by now adding solder to the last pad.
The LM431 is an analog device; it won't "trigger" at a specific voltage. In this circuit, it's functioning as a linear voltage regulator, biasing the gate of the MOSFET at its zener voltage. That's nominally 2.5V, but there's a tolerance of as much as +/-2.2%, depending on which part you buy.
It's probably because the mosfet dosen't turn fully on at 2.7 volts. I would check the on resistance of the mosfet but nothing you can do about it.
How do Julian. Your Blue LED has 0.4 Ohms shunted across it and like you calculated, you would need to be pushing 6.25 Amps through those resistors to get 2.5V to develop across the LED. I'm assuming the LED voltage is closer to 3V? which Ohms Law will tell you, would require 7.5 Amps. Your Supply Voltage is already less than 3V so the LED is never going to light with those values. Intended as friendly help, not a critisism. Thanks for the Videos!
HowDo is
Biggest question is: what is the rds on of the mosfet? If it is equal as the three resistors (at best @2.5V gate) then you only have halve the voltage on the led. Don't think a blue led likes 1.25V. My guess is that the rds on is much higher.
I can't believe that a little measurement was not undertaken to see where the voltage losses were, assuming we just didn't see it.
Your calculator has text placed over the solar panel. It makes me irrationally furious .
I don't understand the point of fake solar panels in calculators. Either put a real one or just nothing at all.
Can't wait to see this all done.
Julian, im pretty sure its not a mosfet on the supercap protection boards, its a BJT and forms together with lm431 a linear regulator. So no chance to lightup a blue LED. They are not digital on/off with a hysteresis. And 6.25A they suppose to never reach that much current. I guess these protection boards are limited around
Yeah, I coming to that conclusion myself.
I like the mention of a supercapacitor lighting project, how about a solar garden light with a big capacitor rather than a battery, i think that would make for an interesting project.
That's a brilliant idea ;) Thanks Mark.
What's the temperature rating of a supercap? That might be a problem - and it wouldn't half need a big box, (unless you could find a long thin capacitor that could hide in the stem)
I think Lidmotor has done that. Check out his auto on off video's
That rotating globe kit has 50 of those little leds, have fun
Use a yellow or red LED they come on at a lower voltage.
you got the same soldering iron as me except mine says a different brand :):) its really good I love my soldering iron I got it for my birthday last year. one thing tho the temperature needed calabrating when I got it it was way hotter than it said on the display like 45 degrees more or smth so maybe check yours too. once I set it tho its been fine since
The mosfet is being used in the linear region as a variable resistor and not turning all the way on. Recall that the gate must be more positive than the drain by the "Vt."
Turns out it's not a MOSFET :)
you could have used your multimeter to measure the voltage drop over the diode and each of the cables separately...
with only 2.5-ish volts as gate voltage it is not surprising that the MOSFET is not fully turned on. Actually a bipolar transistor would have done a much better job here...
If you're going to do any SMD soldering, you should invest in some fine-tip tweezers. I have a pair of Aven tweezers that cost me about $4, but they can probably be had for less.
I actually ordered a set of "7Pcs Anti-Static Tool Plastic Tweezer Heat Resistant" that have some nice tips on them. I got them for this type of work and for desoldering old boards. Costs about $2 from ebay seller wikita.
In my experience amplifiers catch fire mostly because the bias voltage divider resistance is too low. It can also be caused by having the input voltage too high on the primary or secondary stage which can overdrive the FETs causing clipping. If I had more information about the setup of your amplifiers I could probably tell you more as I've built quite a few myself and had to deal with such problems.
Just a minor nitpick about the heat dissipation of those resistors. 2.5/0.4 gets you the amps, but the important figure in resistor heat dissipation is the watts. Those poor little sods are dissipating 15.625 watts!
Actually they didn't - but just because the mosfet wasn't biased and dissipated approx. 90% instead of the resistors.
That mosfet won't dissipate 16W either on that PCB. It will just fry up.
A 700 farad capacitor charged to 2.5 volts is going to contain about 1700 coulombs when fully charged. If you are charging it with 500 mA, it is going to take about 3400 seconds, which is almost an hour, to charge it up. So really, it isn't surprising that the voltage increases very very slowly.
I have that exact soldering iron and straight away i recommend you cut the plug off as it has a shielded earth pin aswell as use a temperature between 330 and 370
This one has a full metal earth pin :)
Placing a bet that you built a Texan amplifier, it was almost mandatory in the 70's !
I can't remember - I think it used power darlingtons. It had smoothing capacitors the size of coke cans.
Julian, have you measured directly, the volt drop across the diode? It might be interesting to observe if it is the same as it is with the leads.
I was thinking the same thing when he was doing a little probing. Find out how much voltage before the diode, after the diode, and at the cap (which he already knew). I was wondering if the power supply was misreading something and giving the wrong value since it can't sense the voltage coming from the cap.
It would certainly be worth having a dig around with the multimeter.
I've heard diodes have a bigger voltage drop as current increases. I haven't tested this myself yet.
true.
Did you double-check that both of the LED connections are actually connected to the board? Could be a bad solder joint, meaning the LED isn't really connected.
I would double check the led and see if maybe the solder has jumped the gap between tracers
Get some rosin flux, either a pen or liquid, apply a drop to the parts before soldering, works wonders. Have a look at Mr. Carlson's Lab channel for some good soldering advice.
I tried to do this last month and ran into the same issue. All of the voltage drop was taking place across the mosfets and got vary hot. One thing I did notice water the current through the mosfet would rise with the voltage.
I didn't think about taking off one of the resistors that sounds like a great idea I'm going to have to try that.
If you removed the middle resistor you could replace it with the led to make it simetrical.
My solder station the same unit burnt out after 3 weeks!
I ended up getting a Precision A55KJ!
With all those eBay, Banggood, AliExpress buys you'd think you own a decend set of tweezers by now to hold those SMD components in place ;-)
Those china cables have 1 Ohm. Throw them away. Had the same ones and got quite the same issues. Since then I solder my own crocodile cables with 2,5² or 4² for low Volate experiments.
Yep, I agree. I'm going to redo my cables as well. I saw a video that showed the resistance before and after, and it was substantial. I just need to get the banana clips ordered.
The protection circuit is working, it's just not protecting anything....
Actually it seems to be working fine. What is the point where it draws no current vs where it starts drawing "some" current. It may be a progressive limiter.
Julian you know the panel that is mounted on the neck of a colour CRT would have three class A amps one for each colour you know R,G,B could you not use that sort of thing and possibly use the third class A amp for the base so Left,Right and Base but it would be a good idea to remove common transistor TR5 which seems to connect the emitters of the class A amps to ground through a current sink, just an Idea.
Maybe try a red LED with a Vf of about 2V
Julian, that's not how you solder. You should have tinned the exposed copper on the board first. That way you could have just heated each pad to melt the solder on both the pad and the LED.
Speaker size is the diameter of the diaphragm
+Sparky Projects That makes more sense :)
Juilian You need to get some flux! Buy a fluix pen or a tin of the stuff.
Would it be better to have the PCB for the caps component facing down to give a bit of protection?
Nice idea :)
The crocodile clip cables are rubbish. I ordered some, not from china and there is barely any copper inside... Gonna replace them with my thick braided red wire I have around, very flexible stuff. Very nice wire. The clip plastic color is enough for me.
Thumbs up for Not sure why my amps caught fire :)
I presume because of high quiescent current and lack of temperature feedback ;)
Yeah, I think one of them was class AB.
Julian, I think your early electronics suffered from misspellings, we're they possibly audio amplifiers? ;-) cheers! And thanks for the show!
i love my katsu and i run it at 350 temp
Are the cheap supercapacitors largely factory rejects and pullouts or what? I see a lot of people finding several in a batch defective or "weak" and sometimes arriving with blobs left over from obvious desoldering.
You should make a capacitor based spot-welder for 18650 batteries.
I thought "never gonna work", as the LED is across a very low resistance - and will a blue even turn on at 2.5V anyway?
And the lead resistance evident on charging is also messing up the voltage reading of the PSU. so for a point before it current limits, you actually have a shunt regulator vs the lead resistance.
Just how much power can a dinky surface mount transistor and some tiny resistors dissipate ?
Google is always listening Julian.
Me too ;)
Shouldn't that diode use .6v?
Have you tested various multimeters to the charger to see what the difference is?
I like that little power supply you're using, where's it come from?
Hi, i like your video's Julian. Do you have a link for the small power regulated supply you used to charge those supercaps ? Thanks.
Sorry, found it ...;-)
Sir,
Its a nice video. I brought the balancing board. I tried testing the balancing board for verifying its regulation by connecting the supercapacitor and a variable power supply to the same slot and used a multimeter to measure the voltage of the supercapacitor. Not sure if the method is right because the multimeter would not be able to show the actual voltage of super cap as the source is also connected to same point. By this method, I find the voltage rising above 2.8V. Didnt check after that. Is there any way to ascertain that regulation is happening? What is the max applicable voltage to the board for the regulation to happen?
So much for not messing with cheap mains products
Use a low power incandescent lamp instead of the LED. They'll last for many years if under-run.
They sell them for a car because of RUclipsr Laserhacker who made a car battery replacement with super/ultracapacitors.
Seems like time to design a protection circuit and build it, because the CotS ones are turning out to be rubbish.
Hi Julian, might I inquire as to the time it takes for the better percentage of your Ebay orders to arrive in the post please :-) I am waiting on some items, solder being one urgent item, that are pushing the 70 day mark currently!! Interested to know the shipping times for EU and GB
i saw adam welch last week
why don't you put the lonley speaker in an pvc tube to make a bass chamber?
When you last used these SC voltage protectors you used a digital version with a voltage checking chip, the ones in this video are analogue using a precision 3 terminal zener to drive an analogue device, I know, I used similar last year and tried your LED idea, it didnt work...
nice new soldering iron
I thought supercaps charged up right away, and the reason that they are being considered or adapted to e -cars
they do, but you´ll need to provide current...usually within 10 to 30Amps...they store a lot of engergy and you need to pump that in....
Check the voltage leaving the buck converter plz.
I don't understand why you are so timid when it comes to the current setting you're using to charge those capacitors...
Here's a thought: How about instead of an LED, connect the input side of an optoisolator across those resistors. Then you can do all sorts of things with the output sides, and it won't depend so much on the exact details of the circuit you're trying to monitor.
adam welch loves you, but we wish he had gifted you a proper bench power supply instead. :D
you should visit his garden once, nonetheless.
hi julian
can i ask you a question please
it is can i run 2 x 5mm led in series from one pin in an arduins
as i want to make traffis lights for a model railway
for a cross road junction i have seen sone done on youtube
but it does not make it very clear as to how they are done
i know that i will need a resistor
but i am worried that the 2 led lighting together will damage the arduino
thanks
james
james o'connell - An arduino's digital pins can handle 2 leds in series just fine. Just be sure to add thir forward voltages when you calculate the resistor value
hi benjamin
thanks for your help
so i would need 1 resistor for each led
and the resistor must be for 5 volts power
is this correct
again thank you for your help
regards
james
Looks like the end screen links are missing.
+The Up Late Geek Thanks, I'll fix that.
i'd bet you dropping the voltage across the jumper leads your using
you didn't link adam welch's channel...
xox
Ah yes, thanks for that. One advantage of early access. Adam will never know ;)
Julian Ilett :-)
I've bought some of those so called Schottky diodes from eBay. I reckon they are just standard diodes. The voltage drop on mine is 0.6v
John Armstrong The voltage drop depends on current flowing through the device, check the datasheet. See the graph named instantaneous forward voltage vs instantaneous forward current.
MrJohhhnnnyyy Ah! Does the voltage drop increase or decrease with current? I was using one of these ebay round 10a ones as a blocker on my solar system and the voltage drop was 0.6v and it got very hot at 5a but it was sold as a schottky. When I changed it for a huge true flat twin Schottky diode out of a pc power supply (using only one side) the voltage drop is only 0.3v and it doesn't get particularly hot?
The voltage drop rises with current. Diodes in that "small" package you refer to have a rating of 5A maximum, usually. So having a 0.6V drop at full current is pretty damn good. The small diode dissipated 0.6V*5A=3W that's why it got hot, the TO-220 package one dissipated only 1.5W. That package can stay reasonably cool at this dissipation level without any heatsink.
MrJohhhnnnyyy I really do appreciate your reply. I have so much to learn and I am enjoying my new hobby. I hope that folks like you will continue to tolerate stupid comments.😄
It's alright, you can't know everything. We all started from zero sometime ago, it just takes time to learn all these tricks. I just found it funny that Julian sounded so confused about it, 'cause he has much experience. He is pretty good at digital stuff, though. Like micro's, logic chips, those Z80's :D I know about diodes and simple analog circuits, but when it comes to micro's and those old processors, I know bugger all :D
Julian how does the protection circuit work if you are charging directly on the + and - terminals
It's shunt protection - current is consumed by resistors (and a transistor) to offset the charging current.
Understood, Thank you
I've owned one very much like that station, it worked very well :)
Bought mine from hobbyking
What happend to it Martin? I have the same one.
Gave it to my father when I bought a digital JBC with sleep function :)
Haha, nice one! I put a neon indicator switch on mine, in order to prevent leaving it on all night long.
I got some fake MOSFETs recently, I wonder if that is a fake Shockley.
I have the same amp board and I connected it to 2 6"/9" 6ohm car speakers. You have to scream over it
You make computers from scratch and you didn't even have a decent iron?!
Flux!!! It will make soldering so much easier.
yes, new vid
That's my issue, I have several multimeter's They all say something different. I can't trust them. My Fluke killed my 18650's because I had it set to 4.15v and it overvolted 4.3v... I figured it couldn't be off that much, but it was... My $25 multimeter is more accurate than my Fluke for low voltage
got a 2 k ohm and 1 k ohm resister an 17 volts in and trying to get 9v out with voltage divider and it dosnt work dno wt to do lol
Learn how to calculate the values for a potential divider. Or cheat:
www.electronics2000.co.uk/calc/potential-divider-calculator.php
You are never going to get 9V with those values.
I am sorry but I dont understand that happens mostly on BigClive and here !
A not-so-tech Tech Guy then? ;)
Maybe you can do better yourself, since those protectionboards have been so dissapointing. Why not design and build your own protection circuit?
RIGHT!
Perhaps it's finally time to do a video on learning how to solder (flux etc) you may find it amusing that we all moan about it, but you have so many subscribers that if you learned then many of them would to...
I'm curious as to why you need the diode in the first place, except to protect against accidental reverse-bias the 1st time. I'd just try some short lengths of 14-16 ga. wire direct from the power supply to the cap to minimize the voltage drop across the connecting leads. Then measure the voltage drops. I don't see how you could get more than .8 volts across the diode without letting the magic smoke out.
I need 1 Hz clock pulse. I don't want to use 555. Any novel ideas?
a cheap gps module off ebay gives out a super accurate 1hz pulse for not much money (and 5v dc)
a 32768hz crystal, very common solution
any cheap electronic clock produces a 1Hz if it has a hand/display for seconds...
f ridge yeah I could just shove in a chip like 4060 but I don't want to use frequency dividers for it. I want to make it very minimalist. Plus it's not novel. As you said, it's very common.
The Soft Machine I want it to be as minimalistic as possible
Voltage drop on your leads.
snap on the iron.
Lead free solder. Best excuse for Brexit, really.
my conclusion, despite you´re needing much more diameter on your cables, these shitty overvoltage protection circuits are the most crappy and dangerous things i came across so far...
Just take a look at the board itself..there is a voltage drop sensor which acts as a Zdiode, but how sharp is its knee when it conducts?
The temperature on that MOSFet is an nice indicator, that there is something fundamental wrong here, as i thing that the output of the overvoltage detetcor isn´t able to drive the mosfet into saturation, thus leaving it somewhere within its linear region, make it dissipating the power instead of sending it straight into these resistors.
Bring your scope to the bench and probe the mosfet gate voltage, and check its datasheet, would be a nice idea..;)
You should really never ever trust these china crap, but test them prior throughout. it´s better being save than sorry, and an exploding superCap is not what you want to ever experience...usually it´ll catch fire and you´ll also have a "wonderful" blowoff as well...
Nice video as always...keep ´em comming :)