Re: Carrier Control Timer (use the COR-2 circuit) The 555 timer is a lot like the 723 (voltage reg) chip in regards to a very large variety of available circuit options and layouts that simply must obey certain rules detailed in the Mfgrs data sheets. Onward...
The 555 is one of the most useful electronic circuit chips ever made. It has a fairly large number of possible simply configured mono & astable (cycle) circuit operations. And it's just as easy to get lost when trying to use it for specific tasks. As in the way of the world... sometimes it's best to see on paper how someone else has already applied the 555 toward x-application and of course use that circuit (aka "steal") for your needs. How that other person has/had completed the interface and trigger requirements using combinations of input & reset pins and some external support parts like transistors and diodes. Working from memory here... the 555 triggers on the rising edge of a changing input. The Original Hamtronics COR-2 circuit was a fairly well thought-out circuit using a 555 chip for the tail and a second 555 as the time-out timer. And because of the way the 555 operates with voltage ratios it was fairly free from problems with more than modest changes circuit supply voltage. Hamtronics moves forward in time with the COR-3 Moving to op-amps to complete timers and audio circuits was done in the Hamtronics COR-3 circuit. Both the mentioned Hamtronics circuits not only work very well for what they are but the builder/operator learned - picked up a fairly clear understanding of how each portion of the circuit works. They aren't teaching this type of stuff in school much anymore... and you get to build it yourself. Nothing more fun for an electronics person than a little of hands-on work with a good set of instructions (RIP Heathkit) in hand. Of course those of you following the Hamtronics line through the years saw the COR-4 circuit with an Eprom for the now on board CW IDer memory element. And Hamtronics has the COR-5 unit, which is a basic micro processor repeater controller. I believe they still offer the cor-4 and maybe the cor-3 circuits. You can pick up a lot of information and skill building kits and Hamtronics is one nifty way to go... I've also seen less informative 555 timer chip kits sold by Ramsey, Electronics Rainbow & Jameco, which are probably the Velleman brand kits supplied with really horible instruction sheets. And of course the "555 Timer Cookbook" should be in your library. cheers, skipp > [EMAIL PROTECTED] wrote: > For some reason I never had much luck with 555s; the trigger > inputs were so sensitive that they always glitched in my > noisy high school-era circuits. I found the LM324 quad op > amp to be much more stable & versatile. One section could > be the COR, another the timeout timer, & yet another the > audio amp/de-emphasis. > Bob NO6B > >The 555 will do the job just fine... you need only configure it > >properly, which for me ended up being the same circuit Hamtronics > >used in their early COR-2 Board. Simply copy that circuit less > >the hang timer portion and you're set. > > > >I wish I could claim credit for it... but the circuit design > >was originally done by Hamtronics (Jerry). I and a few other > >group members can Email you the diagram if you contact us direct > >off the list. Most of us group readers via the web don't receive > >email attachments through the yahoo groups anyway. > > > >The really nice thing about billing things from kits is how you > >end up keeping good circuits around for use in other applications. > >The COR 2 Circuit is a great circuit, wish they still made and > >sold the kit, but now I "roll my own". > > > >cheers, > >skipp
