Science Buddies: "Ask an Expert"

Hello,

I am in China and am trying to do the "Make Your Own Low-Power AM Radio Transmitter" with my son. The Jameco website says that the recommended 1000 Ω to 8 Ω audio transformer is no longer available. I use the specs on the Jameco website (or Mouser) to find equivalent parts here in China. Could you please provide a link for another option for this audio transformer?

I found 2 options on the Mouser website here:
https://www.mouser.com/Power/Transforme ... ?P=1z0wnxy

Should i be looking for a radial transformer or a through hole transformer?
Would this be a good option:
https://www.mouser.com/ProductDetail/Xicon/42TU013-RC ?

I have been able to find a 1300 Ohm to 8 Ohm audio transformer here:
https://detail.tmall.com/item.htm?id=55 ... abbucket=2
It has 4 pins, not 6. Could this work for this project?

Thanks!
'Alim Beveridge

Hi Alim,

Rick knows more about electronics than I do so hopefully he will chime in, but as far as I can tell parts 42TU013-RC, 42TL013-RC, or 42TM013-RC from Mouser would all work (they're all audio transformers with a primary impedance of 1 kOhm and secondary impedance of 8 ohm). They all have different power ratings (look at the "max output" spec on the data sheets) which is the only apparent difference I can find; and the higher the power rating, the higher the price (although not by much).

I'm not sure about the detail.tmall.com item because most of that page is in Chinese - I see "8 ohm" but don't see "1 kOhm" anywhere. If it's also 8 ohm: 1 kOhm then that should work. Four-pin transformers should be fine for this project, the ones with six pins are "center tapped" but this project does not use the center pins (look at Figure 3 in the project's procedure - the center pins are not connected to anything).

I also found this from one of the original sources for the project (not sure if they'd ship to China): https://www.scitoyscatalog.com/product/XFORMR.html

I'm also going to check with Jameco to see if they have a replacement part, but don't see anything else in their catalog right now. Thanks for bringing the broken link to our attention!

Ben

Thanks for the detailed response Ben.

I have found the 42TU013-RC here in China and am ordering it. I figure it's best to play it safe and get the highest power rating.
best wishes
'Alim

alimba - I agree with Ben, the transformer you ordered, 42TU013-RC, should be fine for this application. Just make sure you identify the primary and secondary windings correctly. Ignore the center-taps. If there is a problem and you got the primary/secondary backwards, just reverse the connections, no damage should occur.

Rick Marz

Dear Rick,

thanks for the helpful response.
Kind regards,
'Alim