Re: how to build a very simple repeater controller > How about using good ol' op amps? I like that approach because > almost the entire basic controller can be implemented using a > single chip: 2 op amps for hang time & TOT, 2 left for audio > processing. Add a JFET for squelch audio gating & you're done.
Well... it's been done already many times. The Hamtronics COR-3 circuit is one such well thought out animal. Trying to squeeze it all into one chip package is a noble idea not so easily done. You have to really be good with op amps operating near rf to make the circuit play well. Like the COR-3 circuit mentioned above I used Norton input op amps because their inputs seem to be easier to keep under control in high rf locations. > The TLV2374 features rail-to-rail operation so it makes a good > comparitor, yet also has good audio distortion characteristics > so long as the output stays at least 1.4 V away from the positive > supply rail. It's a good choice for such multi-purpose use. > Bob NO6B Tis a good chip but needing more rail-to-rail output swing was never my design problem. Keeping rf under control with high gain op amps sometimes requires a whip and chair. I should also mention the same functions have been done with Nand gates, buffers and various logic chips including schmidt trigger devices. All the mentioned make great radio receivers if you're not paying attention. I won't admit in this post why I know the above fact... cheers, skipp
