Good day to all. One of the people with whom I work regularly wants to use analog=20 Motorola base radios as an extension of the Intercom systems that I=20 work with. We normally use a GPIO line from the Intercom system to=20 control transmitter PTT but we now have an application where VOX is preferr= ed. Some of the Motorola radios we have available are capable of both=20 digital and analog transmission. These already have a short audio=20 delay of somewhat less than 100ms which does work well. However, for=20 various reasons, the radios that we want to use in this particular=20 project are analog-only and do not have an audio delay available. What the audio delay does is ensure that the first word of a=20 transmission that is triggered by VOX is not lost. That is: the=20 person begins to speak, the radio is immediately put into YX mode,=20 then the delayed audio is fed to the transmitter. This allows the=20 entire beginning of the transmission to be heard by the recipients=20 without losing the first word or two. I used to build something like this many years ago, using Reticon=20 bucket-brigade delay chips. Those have now vanished. The easiest solution for me is to simply find something that is=20 available off-the-shelf at reasonably-low cost. Barring that, modern=20 PIC chips have enough RAM to buffer 100ms of audio at a reasonable sample r= ate. Two questions: 1) Is anyone aware of a readily-available audio delay module at=20 reasonable cost? I just need the bare PCB since this module would be=20 incorporated with the remaining electronics needed. 2) Is anyone aware of a pre-existing PIC project that I can clone /=20 modify as needed for my needs? I would prefer a minimum of external=20 components: use both the on-board A/D and either PWM or DAC to=20 reconstruct the output audio. Unbalanced audio for both input and output, audio level not critical,=20 prefer 10 bit or 12 bit resolution simply to maximize the available=20 dynamic range. Frequency response up to 5 KHz (or higher) preferred=20 - the communications radios are already pretty brutal and I don't=20 want to degrade that further with the delay circuit. If there is a suitable PIC design, I'd prefer to work with the PIC16F=20 family as opposed to the PIC18F. However, I'll take what ever is available= .. Many thanks! dwayne --=20 Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA 780-489-3199 voice 780-487-6397 fax 888-489-3199 Toll Free www.trinity-electronics.com Custom Electronics Design and Manufacturing --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .