Film-Tech Forum ARCHIVE: Simple Cue Detectors

This is topic Simple Cue Detectors in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

To visit this topic, use this URL:
https://ft-forum.com/ft/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=007165

Posted by Laurence Hammett (Member # 1134) on 05-06-2005, 01:04 PM:

I just bought 10 Cue detector/fail safes from Big Sky. I liked the Idea that they would use other than unreliable foil tape to function. Problem is that their simple device doesn't really provide a dry contact. Its sensor simply puts out 200mv when it reads the cue and that won't activate the relays on my maxi 10's in most cases. Does anyone know what I could put this 200mv across that would result in a dry contact fort he automation. I tried getting relays that didn't require much to activate them but no luck.

Any Ideas

Posted by Stephen Furley (Member # 1277) on 05-06-2005, 01:24 PM:

Sounds like you'd need to use the signal from the detector to switch a transistor, and that would then operate the relay. Exact circuitry would depend on various factors, how much current the relay coil takes, whether you need the relay to be energised or de-energised when the cue is detected, etc.

Posted by Randy Stankey (Member # 64) on 05-06-2005, 02:16 PM:

Try hooking up a 555-Timer or a 74121-IC as a one-shot trigger.

A 555 can take up to 5v as input and SHOULD trigger on 250mv if you set it up right. It can power a small relay or other device.

That ought to get you where you want to go.

Most of the parts you need can be picked up at Radio Shack, et. al.