Good stuff. Thank you, Nick. It's much easier than I remember from my school days. As it's impossible that my IQ has magically increased over the last 25 years, it seems, that you can explain things much better.
Great video Nick. Maybe you can explain how to find the beta and Early voltage in the model statement in LtSpice. Maybe explain some of the other parameters as well.
Hi James, thanks very much. That would be a whole other video. I don't know about calculating the Early Voltage - I've only ever come across approximations of it. Calculating beta is easy in LTSpice though. You just create a trace for the collector current, right click it at the top of the trace window and edit it to read: Ic(Q1)/Ib(Q1). This assumes your transistor is labelled Q1. You'll then get a trace for Beta. At some point I'll probably do a video on it but in the meantime there are a stack of other Small Signal Analysis videos using LTSpice. Thanks again. Best wishes, Nick
VERY well done Nick. I cannot really fault it, and yes id did bring back memories of my old lecturer trying to demonstrate the use of the bypass cap by jumping up and down. The only point I cam make is that right at the beginning you said that you changed the current from 10mA down to 8,5mA It would have been interesting to know what led you to that value Obviously once you know the current them working out the resistor values is as before i.e I think the load in analysis would have been worth while including. (maybe as a quick video supplement) Andy
Thanks very much Andy. I did contemplate going into my thinking behind changing IC to 8.5 mA but it was really just a question of time. Load Line Analysis is another massive rabbit hole that I've been down in the course of producing these last two videos. I think it is fascinating stuff and perhaps something I can return to at some stage. In the meantime, if you are interested I discovered an excellent 4 part series on this on the Electronics for the Inquisitive Experimenter RUclips channel: Part 1 is here: ruclips.net/video/-fQotNX3gT0/видео.htmlsi=s7EIEZ3dGYiagb7C It is very thorough but Ralph explains everything brilliantly and it is clear and easy to follow. Hope this helps. Thanks again. 73, Nick
Hi there! Thank you very much. Here is the reason we add +1 to Beta when we are at the emitter. Beta is the gain of the transistor. So the collector will see the base current multiplied by Beta. The emitter will see the same (although in phase with the base - unlike the collector) but it also sees the original base current which flows from the base to the emitter (not to the collector). So the emitter sees B+1. In all practical reality you can pretty much ignore the +1 as the base current is so much smaller than the emitter current. This also allows us to approximate that the collector current = the emitter current. Hope this helps. Best wishes, Nick
Very interesting thanks Nick. What are the implications of connecting the first stage output of 602R to the second stage input of 2.3k? Perhaps irrelevant at audio but needs consideration (impedance matching?) at higher frequencies?
Hi Nev, thanks very much. You raise an important point. For audio it would have been advantageous if I had managed to get the input Z of the emitter follower a bit higher so as to preserve more of the voltage gains in the first stage. At audio I aim for a factor of 10 i.e. input Z is 10 times higher than output Z of the stage feeding into it. Here I only managed 3.8. With some optimising this could be improved. When it comes to RF you are totally right. Impedances need to be matched for maximum POWER gain. I would probably tweak the 602Ω output Z of the first stage a bit and then connect the two stages with a 1:4 transmission line transformer. Thanks again for watching and for your insightful question. 73, Nick
@@M0NTVHomebrewing great question and the answer, I was always wandering though, why it is so important to impedance match the rf but it is not the same for the audio. I meant from logical perspective it should be the same shouldn’t it?
The short answer to that question is that signals operate differently at different frequencies. At RF frequencies where the wavelength is short enough to make a difference then impedance mismatches mean signal reflected back. This produces standing waves (SWR) and can result in distortion of the original signal. This is particularly the case if it is reflected back into something like a mixer which can then produce spurious outputs. But chiefly we want to preserve POWER transfer at RF - and max power transfer happens when impedances are matched. For audio signals it is different. The wavelength is so massive as not to interfere in the way that it does at higher frequencies. Max VOLTAGE transfer is king here. Ideally you want an input Z much higher than the output Z of the stage feeding it. This preserves the voltage gains and also doesn't load down the previous stage. You can boost power when you need it (e.g. to drive a speaker). Hope this helps. 73, Nick
Thanks. I didn't actually use a common base amplifier in my design so I didn't tackle it. I just covered the two I did - common emitter and common collector (emitter follower). In any case I was way out of time. Perhaps that can be a video for another day. Thanks again. 73, Nick
well, all is clear. however why not to prove all the theory on practice. it would be of great importance to all people. show how the signal changes if (or when) u change a parameter.
Hi Sergey, yes, I agree it would have been good but the constraints of time just got the better of me. I'm afraid that will have to be another video for another time. Thanks for watching. 73, Nick
@@M0NTVHomebrewing Nick, thanks for your fast reaction. u really keep your hand on the pulse, so to say. as to the comment... sure it would take a lot of time, energy and wish to do it. i will keep on regularly come here and watch your very good videos, thanks again...
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Good stuff. Thank you, Nick. It's much easier than I remember from my school days. As it's impossible that my IQ has magically increased over the last 25 years, it seems, that you can explain things much better.
Hi Michal, thank you very much. I'm pleased it helped. Best Wishes, Nick
Thanks so much Sir for your detail explanation. I learned a lot for this and the previous videos.
Thanks M0NTV for the breathtaking simplification of a complex subject, for simple minds like mine.
Thanks David. It is a subject I've been wrestling with myself for a few years now. I'm pleased it made some sense! Best wishes, Nick
The world's best teacher thanks sir
Thank you very much Kabanda. That's very kind of you. Best wishes, Nick
Thank you, thank you, THANK YOU!!when I think I know it all, you slap me upside the head..Great video
You are welcome Ed. Thanks for watching as always. Best wishes, Nick
Cool Video, Nick!
Thanks very much! Hope you're doing OK. Best wishes, Nick
Well presented. Thank you
Thanks very much. 73, Nick
Excellent video for its content and production.
Thanks very much Tom. 73, Nick
Thank you so much for posting this video! I was beginning to go through withdrawal waiting for this.
Cheers Don. Hope it was worth the wait!!! Look after yourself. 73, Nick
Great video Nick. Maybe you can explain how to find the beta and Early voltage in the model statement in LtSpice. Maybe explain some of the other parameters as well.
Hi James, thanks very much. That would be a whole other video. I don't know about calculating the Early Voltage - I've only ever come across approximations of it. Calculating beta is easy in LTSpice though. You just create a trace for the collector current, right click it at the top of the trace window and edit it to read: Ic(Q1)/Ib(Q1). This assumes your transistor is labelled Q1. You'll then get a trace for Beta. At some point I'll probably do a video on it but in the meantime there are a stack of other Small Signal Analysis videos using LTSpice. Thanks again. Best wishes, Nick
👍Thank you sir.
Glad it was of some help. 73, Nick
VERY well done Nick.
I cannot really fault it, and yes id did bring back memories of my old lecturer trying to demonstrate the use of the bypass cap by jumping up and down.
The only point I cam make is that right at the beginning you said that you changed the current from 10mA down to 8,5mA It would have been interesting to know what led you to that value
Obviously once you know the current them working out the resistor values is as before i.e I think the load in analysis would have been worth while including. (maybe as a quick video supplement)
Andy
Thanks very much Andy. I did contemplate going into my thinking behind changing IC to 8.5 mA but it was really just a question of time. Load Line Analysis is another massive rabbit hole that I've been down in the course of producing these last two videos. I think it is fascinating stuff and perhaps something I can return to at some stage. In the meantime, if you are interested I discovered an excellent 4 part series on this on the Electronics for the Inquisitive Experimenter RUclips channel:
Part 1 is here: ruclips.net/video/-fQotNX3gT0/видео.htmlsi=s7EIEZ3dGYiagb7C
It is very thorough but Ralph explains everything brilliantly and it is clear and easy to follow.
Hope this helps. Thanks again. 73, Nick
@@M0NTVHomebrewing thanks, I have a peek atit and see how much I remember 🙂
No worries Andy. Cheers!
Mate, that was heavy for a Sunday morning. Nicely done though!
Cheers Al!
Excellent video. Just one question, why do we need to add +1 to the Beta?
Hi there! Thank you very much. Here is the reason we add +1 to Beta when we are at the emitter. Beta is the gain of the transistor. So the collector will see the base current multiplied by Beta. The emitter will see the same (although in phase with the base - unlike the collector) but it also sees the original base current which flows from the base to the emitter (not to the collector). So the emitter sees B+1. In all practical reality you can pretty much ignore the +1 as the base current is so much smaller than the emitter current. This also allows us to approximate that the collector current = the emitter current. Hope this helps. Best wishes, Nick
Thumbs up thank you❤
Thank you very much. Best wishes, Nick
Very interesting thanks Nick. What are the implications of connecting the first stage output of 602R to the second stage input of 2.3k? Perhaps irrelevant at audio but needs consideration (impedance matching?) at higher frequencies?
Hi Nev, thanks very much. You raise an important point. For audio it would have been advantageous if I had managed to get the input Z of the emitter follower a bit higher so as to preserve more of the voltage gains in the first stage. At audio I aim for a factor of 10 i.e. input Z is 10 times higher than output Z of the stage feeding into it. Here I only managed 3.8. With some optimising this could be improved.
When it comes to RF you are totally right. Impedances need to be matched for maximum POWER gain. I would probably tweak the 602Ω output Z of the first stage a bit and then connect the two stages with a 1:4 transmission line transformer.
Thanks again for watching and for your insightful question. 73, Nick
@@M0NTVHomebrewing great question and the answer, I was always wandering though, why it is so important to impedance match the rf but it is not the same for the audio. I meant from logical perspective it should be the same shouldn’t it?
The short answer to that question is that signals operate differently at different frequencies. At RF frequencies where the wavelength is short enough to make a difference then impedance mismatches mean signal reflected back. This produces standing waves (SWR) and can result in distortion of the original signal. This is particularly the case if it is reflected back into something like a mixer which can then produce spurious outputs. But chiefly we want to preserve POWER transfer at RF - and max power transfer happens when impedances are matched.
For audio signals it is different. The wavelength is so massive as not to interfere in the way that it does at higher frequencies. Max VOLTAGE transfer is king here. Ideally you want an input Z much higher than the output Z of the stage feeding it. This preserves the voltage gains and also doesn't load down the previous stage. You can boost power when you need it (e.g. to drive a speaker).
Hope this helps. 73, Nick
Nice!
What about common base?
Thanks. I didn't actually use a common base amplifier in my design so I didn't tackle it. I just covered the two I did - common emitter and common collector (emitter follower). In any case I was way out of time. Perhaps that can be a video for another day. Thanks again. 73, Nick
@ sure! Thanks for the video, it’s real cool stuff!
Thanks again :)
Are those electrolytic caps? If so, which side is the -?
Hi Justine. Yes they are all electrolytic caps. The cathodes (-) are black and the anodes (+) white. 73, Nick
well, all is clear. however why not to prove all the theory on practice. it would be of great importance to all people. show how the signal changes if (or when) u change a parameter.
Hi Sergey, yes, I agree it would have been good but the constraints of time just got the better of me. I'm afraid that will have to be another video for another time. Thanks for watching. 73, Nick
@@M0NTVHomebrewing Nick, thanks for your fast reaction. u really keep your hand on the pulse, so to say. as to the comment... sure it would take a lot of time, energy and wish to do it. i will keep on regularly come here and watch your very good videos, thanks again...
Thank you Sergey :)
The world's best teacher thanks sir
Thank you Aran for your kind words. I'm glad it was useful. Best wishes, Nick