How an Amplifier works - amplifier with gain control 

I'm from India , I'll have to pay in dollars, and how much

Glad you enjoyed it!

Glad you liked it!

​@@AllElectronicsChannela bypass cap parallel to emiter resistor woul do the same job right?

Yep

Very nice, come back with the results !

Welcome!

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!

Hi friend! It is not Spanish hehe

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?

I'm designed it for 4.9MHz

It is!

0 to 1mA, 0 to 10V

Yep!! Would be nice to take a look on a broader span

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

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

I think that any modern transistor can accomplish that. Take a look at BFR92A

@@AllElectronicsChannel thanks

@@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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hahahaha