Thumbs up for a very nice approach and presentation. I will simulate the circuit to get additional insight, but it would be interesting to compare this approach with one that reduced gain by increasing negative feedback.
Hey Love your channel, can’t find many others out there like it! Could you do a video on Automatic Gain Control? Is it possible to make one with a very wide band frequency response? I would like to figure out a design that could be used as an attenuator with constant pk-pk amplitude across wide range of frequencies
@@AllElectronicsChannel Never used any specific components like PIN diodes before, I’m always trying to develop strategies with just BJTs the hard way :) and I always use breadboards, but seriously need to move to pcbs for RF projects soon. But on a breadboard I have built a 27, 56, and even recently a 227MHz transmitter and receiver with just BJTs and typical passive components all on a breadboard. Simple on/off is all. The 227MHz transceiver was quite unstable as you might imagine though and only had a range of up to 7ft basically at best, but quite cool it worked at all on breadboard, it was super-heterodyne type, single stage mixer, IF of 1-10MHz (very unstable of course). It’s really a challenge when the whole supply rail has 200mVpp noise at 227MHz and any inductors above 5uH act more like large caps and several insulated rows 5 spaces apart or even 10 acts as a pretty good coupling capacitor haha very frustrating to work with breadboards at RF but it can be done somewhat.
@@issacs740 hahaha very nice!! go to copper single layer pcb as breadboard, will be a new life. 1N5819 work great as poor man PIN diodes, try to make a simple PI atennuator using it
Turn ratio for a normal transformer would be sqrt(Za / Zb), for an auto transformer you subtract 1 (to consider the primary as part of the secondary also)
Why in most rf common emmiter amplifiers we add an inductor to collector for increase impedance or resistance at the collector?? Why don't use just a resistor ???
This is called inductive peaking. It will enhance the bandwidth of the amplifier, creating a little more gain at higher frequencies, compensating a little the natural rolloff of the amplifier.
hello, nice circuit, I also did two calculations and I believe you have a very good gain, using that polarization you have more than 500 of hfe with that model of transistor, pero one thing I can't understand, the ratio of the auto transformer why you chose that number of turns for a 700 ohm at 50 ohm, are you sure? that you leave 2 mA to the transitor not to saturate it and the remaining of 10 mA for the output with a 50 ohm load?
Hi Matteo, with the ratio I used on practice we are using a little more current, using a litter lower collector impedance. The beta of the transistor is much lower at higher frequencies, you can aproximate by Hfe / f
@@AllElectronicsChannel an figured out for hfe, and is there a rough calculation to know how many turns you need to have to have a ratio from 700 ohms to 50 ohms? because I thought it was 14:1, then maybe I'm wrong
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I'm from India , I'll have to pay in dollars, and how much
Great electronic video!! Thank you Mr.Eng. Greg.
Thank you! Glad you enjoyed it.
Thumbs up for a very nice approach and presentation. I will simulate the circuit to get additional insight, but it would be interesting to compare this approach with one that reduced gain by increasing negative feedback.
Very nice, come back with the results !
Hey Love your channel, can’t find many others out there like it!
Could you do a video on Automatic Gain Control? Is it possible to make one with a very wide band frequency response? I would like to figure out a design that could be used as an attenuator with constant pk-pk amplitude across wide range of frequencies
Thanks! Nice topic. Probably a diode detector and a PIN attenuator should get good bandwidth response
@@AllElectronicsChannel Never used any specific components like PIN diodes before, I’m always trying to develop strategies with just BJTs the hard way :) and I always use breadboards, but seriously need to move to pcbs for RF projects soon.
But on a breadboard I have built a 27, 56, and even recently a 227MHz transmitter and receiver with just BJTs and typical passive components all on a breadboard. Simple on/off is all. The 227MHz transceiver was quite unstable as you might imagine though and only had a range of up to 7ft basically at best, but quite cool it worked at all on breadboard, it was super-heterodyne type, single stage mixer, IF of 1-10MHz (very unstable of course). It’s really a challenge when the whole supply rail has 200mVpp noise at 227MHz and any inductors above 5uH act more like large caps and several insulated rows 5 spaces apart or even 10 acts as a pretty good coupling capacitor haha very frustrating to work with breadboards at RF but it can be done somewhat.
@@issacs740 hahaha very nice!! go to copper single layer pcb as breadboard, will be a new life. 1N5819 work great as poor man PIN diodes, try to make a simple PI atennuator using it
@@AllElectronicsChannel huh interesting, I will definitely have to check that out, thanks!
Also is this applicable for a particular frequency?
I'm designed it for 4.9MHz
Thanks for the excellent explanation of this!
Glad you enjoyed it!
Your explanation of this complicated subject is clearly understandable. Thank you!
Welcome!
i saw spanish books in your lab, have you a channel in spanish too?
Hi friend! It is not Spanish hehe
Gregory, is a current mirror with beta helper on the right ?
It is!
Hi great video. I don't understand how you come up with the turns ratio of the coil or auto transformer.
Turn ratio for a normal transformer would be sqrt(Za / Zb), for an auto transformer you subtract 1 (to consider the primary as part of the secondary also)
@@AllElectronicsChannel Would you show the calculation please?
Why in most rf common emmiter amplifiers we add an inductor to collector for increase impedance or resistance at the collector?? Why don't use just a resistor ???
This is called inductive peaking. It will enhance the bandwidth of the amplifier, creating a little more gain at higher frequencies, compensating a little the natural rolloff of the amplifier.
@@AllElectronicsChannel thanks
What is the range of the bias voltage on the diode? 0 to 1 volt?
0 to 1mA, 0 to 10V
But this will change the frequency response as the gain changes right?
Yep!! Would be nice to take a look on a broader span
thumbs up, i have a signal of -45 db at 122mhz, how best do i amplify the signal to up to 20db
I think that any modern transistor can accomplish that. Take a look at BFR92A
@@AllElectronicsChannel thanks
hello, nice circuit, I also did two calculations and I believe you have a very good gain, using that polarization you have more than 500 of hfe with that model of transistor, pero one thing I can't understand, the ratio of the auto transformer why you chose that number of turns for a 700 ohm at 50 ohm, are you sure? that you leave 2 mA to the transitor not to saturate it and the remaining of 10 mA for the output with a 50 ohm load?
Hi Matteo, with the ratio I used on practice we are using a little more current, using a litter lower collector impedance. The beta of the transistor is much lower at higher frequencies, you can aproximate by Hfe / f
@@AllElectronicsChannel an figured out for hfe, and is there a rough calculation to know how many turns you need to have to have a ratio from 700 ohms to 50 ohms? because I thought it was 14:1, then maybe I'm wrong
The impedance transform is the square of the turns! For an auto transformer you need to add + 1.
So (7/3 + 1)^2 in this case
Very nice!
Superb !
0:04
I want to be knowledgeable like you in electronics , guide me
@@MrDacorp I'm an EE student but I would like to have recommendations on books courses etc.
@@complex_variation Sir please suggest some books , covering basic knowledge to advance
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The video is good but your soldering skills need a check
hahahaha
Very nice!