I'm very happy with the ID-O-Matic - hard to beat for $20! http://www.hamgadgets.com/product_info.php?products_id=64
Bill - WB1GOT --- In Repeater-Builder@yahoogroups.com, "skipp025" <[EMAIL PROTECTED]> wrote: > > 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 >
