[TenTec] Using a comptuer microphone with a Triton 4 (544)

[Dr. Gerald N. Johnson]

On Thu, 2007-11-15 at 21:41 +0200, Geoffrey S. Mendelson wrote:
> I recently purchased (for $5) a headset designed for computer use. It's
> the "closed" design, so while to me it eventually becomes uncomfortable,
> before that it makes listening easier by reducing external noise.
> 
> The microphone, is a low voltage condenser unit that requires DC.
> A computer sound card puts out five volts, but I think that much
> less will do. 
> 
> I would like to use this on a Triton IV (D) (model 544), which does not
> provide DC. I'm looking for a circuit that would allow me, with a minimum
> of parts (parts are hard to find here), to use it.

As a first shot, supply 5 volts (maybe 4.5 from three AAA cells) to the
microphone through a 680 series resistor. Couple to the radio through a
0.1 mf disc ceramic capacitor. Probably don't go lower than 330 ohms or
higher than 1K, capacitor between .01 and .5 mf.
> 
> I expect that I could use a three volt lithium cell and a current 
> limiting resistor to provide the DC, and then use a capacitor 
> to block the DC on the input of the radio. I would then have
> to use VOX, or an external transmit switch.

Yup. Lots of operators like a foot switch.
> 
> Any suggestions?
> 
> Thanks in advance,
> 
> Geoff.

73, Jerry, K0CQ