Help me with a circuit (audio relay)

[sinkplaat]

Audio relay alternative

Hi,

I have a circuit that needs to switch the audio between a telephone headset and the telephone into an effects circuit. When the circuit has no power, the unit needs to switch the headset back to the phone, bypassing the effects unit by default.

I'm currently using relays as shown below, but the current drain from the coils are unacceptably high, could anyone suggest an alternative?

Thanks,

 

[hcet]

Re: Audio relay alternative

Do it in silicon

Try www.fairchildsemi.com or para.maxim-ic.com look for audio switches

There're also many other providers of these ICs.

Design your own circuit

ep20k

 

[sinkplaat]

Audio relay alternative

Thanks, I've used silicon audio switches before, but as I stated above, I need the switch to conduct in the normally closed state when NO POWER is available, silicon switches would not.

 

[hcet]

Re: Audio relay alternative

What is the amont of current in your application?

ep20k

 

[jzo777n]

Re: Audio relay alternative

I have used in some project optically isolated MOSFET relays which is normally closed (depletion fet).
I am not sure how they perform in an audio application
You need about 3 mA for the LED.
Panasonic is one manufacture http://pewa.panasonic.com/pcsd/product/pmos/index.html
But there are other ones also.

Perhaps you can use a combination of enhancement and depletions FET's for the switch function and skip the MOSFET relay.

 

[hcet]

Re: Audio relay alternative

I have used in some project optically isolated MOSFET relays which is normally closed (depletion fet).
I am not sure how they perform in an audio application
You need about 3 mA for the LED.
Panasonic is one manufacture http://pewa.panasonic.com/pcsd/product/pmos/index.html
But there are other ones also.

Perhaps you can use a combination of enhancement and depletions FET's for the switch function and skip the MOSFET relay.

Excellent

Never heard of these bugs. Helped me! I gave you 7 points

ep20k

 

[Siniša]

Re: Audio relay alternative

You could use bistable relay instead. Current is needed only to change state of relay. Capacitor can store energy needed for switching and current required by system would be negligable.

For example: **broken link removed**