How about running the bias through the coil of an in line small relay. It is held in any time the negative voltage is present. The present final cathode to ground circuit would be run through the normally closed relay points. Loss of any bias current and the relay cuts off the finals. Boyd W0BUW
Bill Horne <[EMAIL PROTECTED]> wrote: Bill Horne made an utterance to the drakelist gang ---------------------------------------------------------------------- Mike, I understand, and perhaps "Crowbar" is the wrong term: there's certainly enough technical expertise on the list to suggest a viable circuit. Here's my idea: if bias drop below 50% of normal, then we could trigger an SCR to short the AC source and blow the fuse. 73, Bill W1AC Mike Bryce wrote: > > Mike Bryce made an utterance to the drakelist gang > ---------------------------------------------------------------------- > Gosh.. > > I thought about that, but here's no way to crowbar the bias circuit. > > in the old supplies, the damage is caused by a "lack" of bias. So, if > there is a failure of the bias supply, i.e. it quits, how can you fix > that? > > the only way I could come up with would have been a system that > deprives the transformer of it's primary voltage, shutting down the > supply. It would have to default in the off position too, as you would > not want the supply to cycle on, find the missing bias, then shut > down, the power up, find the missing bias supply, shut down and on and > on. > > > mike > > Mike, WB8VGE > SunLight Energy Systems > The Heathkit Shop > http://www.theheathkitshop.com/ > J e e p > o|||||||o > Note: No trees were killed in the sending of this message, but a large > number of electrons were terribly inconvenienced > > > On Dec 15, 2007, at 5:28 PM, Bill Horne wrote: > > > Bill Horne made an utterance to the drakelist > gang > ---------------------------------------------------------------------- > Is there a provision in the kit for a crowbar circuit to safeguard the > rig if the bias (or other) supply fails? > > Bill, W1AC > > > > ---------------------------------------------------------------------- > Submissions: [EMAIL PROTECTED] > Unsubscribe: [EMAIL PROTECTED] - unsubscribe drakelist in > body > Hopelessly Lost: [EMAIL PROTECTED] - help in body of message > Zerobeat Web Page: www.zerobeat.net - sponsored by www.tlchost.net > ---------------------------------------------------------------------- > -- Lookng back through time you know its clear that i've been blind I've been a fool To open up my heart to all that jealousy that bitterness that ridicule David Gray ---------------------------------------------------------------------- Submissions: [EMAIL PROTECTED] Unsubscribe: [EMAIL PROTECTED] - unsubscribe drakelist in body Hopelessly Lost: [EMAIL PROTECTED] - help in body of message Zerobeat Web Page: www.zerobeat.net - sponsored by www.tlchost.net ----------------------------------------------------------------------
