Need help identifying these transformers..

[shamooooot]

Hello guys

I am struggling to find what transformers are these , and I don't even know where to start as all the resources I found didn't get to mention them!.



1- T2 and T3 in this Push-pull amplifier with double final stage circuit:



2- T1 Transformer-Coupled Amplifier circuit:



3- L1 in Hartley generator circuit:



4- T1 in Astable multivibrator:




5- T1 in AM circuit which is different from the above 4:

[Kim Christensen]

Those above are old school audio transformers that were used in transistor radios in the 1960's and 70's. They'll be hard to find today.
Though I did find some on mouser. I believe the red output one (T3 in Push-pull amplifier OPT) is a 42TL013-RC. T2 (IPT) is probably a 42TL002-RC.



This another transformer (Probably 455Khz IF) that was also used in old radios.


Is there any reason you want to build these old circuits? You can get better audio amps on a single IC these days. Or build a different transformerless design.

[shamooooot]

I appreciate your reply Kim..

Actually I am building these PCB's for educational purposes for the students.

Are there common values for these transformers or is there a way to find out their parameters. We can create these transformers if they aren't available anymore.

[Kim Christensen]

T3 in Push-pull amplifier might be a 42TL013-RC. T2 (IPT) is probably a 42TL002-RC. See my edit (Mouser link above)

[xavier60]

Assuming the transformers are found, the biasing for Q5 might have trouble.

[Kim Christensen]

Dug up a bit more info on old IF transformers.
Since they show (C9 47pF) in the AM circuit diagram. It's probably one without a built in capacitor such as the 42IF104. Though you could use a 42IF101 or 42IF301 if you eliminated C9.

In the end, I think you're just going to have to buy some samples from Mouser and build the circuits to verify that they work as intended and that you've got the right parts. Then order enough for your students. Or find a site that gives you better info about the parts used in their circuits. Where did you find those diagrams anyway?

[xavier60]

This AM receiver kit has audio transformers, https://www.aliexpress.com/item/1005004064556135.html?spm=a2g0o.productlist.main.91.642d6205Izj7hS&algo_pvid=ea05f3fb-c71b-4572-8874-84137b5dd894&algo_exp_id=ea05f3fb-c71b-4572-8874-84137b5dd894-45&pdp_npi=3%40dis%21AUD%219.31%218.56%21%21%216.08%21%21%40210219c216887633155036858d073a%2112000027917991635%21sea%21AU%21130254308&curPageLogUid=YDt0Q0t3lbSM