I apologize in advance for my inexperience.

I've started working on a [hopefully] simple project.

I want to safely connect low impedance stereo headphones (16ohms) to a high impedance intercom (500ohm).

Mouser has a 500ohm primary / 16ohm secondary audio transformer:
http://www.mouser.com/ProductDetail/Xicon/42TM026-RC/?qs=LQJGOuQCHKSqrkgpQIuPNg==

I believe I would need one transformer for each of the stereo channels. Ultimately I'd also like to also add a stereo pot for volume.

I've googled extensively, but haven't been able to find an example of a similar circuit.

could anyone provide some ideas on how to best build this circuit?

Thanks!

 

How many audio channels do you have?

 

it's stereo, so L and R.

 

A transformer might pickup mains hum if a power transformer is nearby. Also the step-down transformer will reduce the level a lot.

Instead, you need a little stereo power amplifier like a TDA2822M. Use a 10k stereo audio-taper volume control.

 

thanks for the responses.

assuming i wanted to try a passive solution (without the amplifier) first, how would i go about wiring everything?

is it as simple as connecting the line from the intercom to one of the primary(500ohm) leads, grounding the other primary, and then connecting one of the secondary leads to the headphone jack and grounding the other?

or do i need some additional components? (resistors, capacitors, etc.)

thanks, and sorry if my questions seem novice.

 

thanks for the responses.
is it as simple as connecting the line from the intercom to one of the primary(500ohm) leads, grounding the other primary, and then connecting one of the secondary leads to the headphone jack and grounding the other?

As simple as that.
Did you try the headphones straight to the intercom? That could also work, but might as well destroy the output of the itercom, especially when set to high volume.

 

damaging the intercom is my main fear.

is there a way to test the impedance of the headphones and the circuit before trying it with the intercom?

 

How do you know that the intercom can drive 500 ohms? Speakers are not 500 ohms.

 

aviation headsets are typically between 300 and 600 ohms. the specs on the intercom show 150ohms as the minimum. and if i understand it correctly, you won't damage an amplifier by presenting a higher impedance load.

i was estimating 500ohms because the 500ohm/16ohm audio transformer was the closest i could find at mouser...