Hello, I am looking for how best to construct what I think may be called a "non retriggerable monostable".
The situation:
I want to remotely trip shutters on a set of 80's era SLR film cameras. These feature electromagnetic shutters, which need only be shorted to ground. I've already made custom electronic switch cable releases that work nicely.
For remotely switching, I believe a small relay will do the trick as far as completing a circuit to ground on the shutter releases, but the trick now is how to remotely actuate the relay.
So, for the "remote" actuation, I purchased an RF doorbell set and took apart the receiver. (Coincidentally, after I bought the doorbell kit, I found a nice write up on using this very RF doorbell rig from John at www.hackersbench.com.) The receiver outputs a signal of about 3 seconds duration to a transistor to which a speaker is attached.
Okay, connecting the transistor output of the doorbell receiver to a relay might work, but I want more control over the time duration. So I figure a 555 timer circuit in a "oneshot" mode would work. I would be able to change the R/C network to be able to have an output time duration of anywhere from 0.1s to 30s.
The doorbell receiver is powered by two C cells (3V), and I would like to run the 555 timer circuit and relay off the same battery source. So, I purchased some low power (CMOS I guess?) TS555IN timer chips. I made a test circuit as seen by Tony van Roon here: http://www.uoguelph.ca/~antoon/circ/pulsetimer.html
It works fine, and I can tailor my output time duration by changing the resistor/capacitor network.
I then substituted transistor Q1 of Tony van Roon's circuit with the output transistor of the doorbell circuit in my test 555 timer breadboard. The RF doorbell receiver output indeed triggers my timer circuit, however, the duration of the R/C network in the timer circuit is apparently being overridden by the long duration trigger from the doorbell circuit. How do I make the output "unresponsive to long duration or repeated input triggers".
The allaboutcircuits chapter about monostable multivibrators says it's possible, but I don't know how.
One more issue: how do I get the timer circuit to NOT do an output when I apply power to the circuit?
Hopefully I've made myself clear. Any help is appreciated! Thanks!
Dave
The situation:
I want to remotely trip shutters on a set of 80's era SLR film cameras. These feature electromagnetic shutters, which need only be shorted to ground. I've already made custom electronic switch cable releases that work nicely.
For remotely switching, I believe a small relay will do the trick as far as completing a circuit to ground on the shutter releases, but the trick now is how to remotely actuate the relay.
So, for the "remote" actuation, I purchased an RF doorbell set and took apart the receiver. (Coincidentally, after I bought the doorbell kit, I found a nice write up on using this very RF doorbell rig from John at www.hackersbench.com.) The receiver outputs a signal of about 3 seconds duration to a transistor to which a speaker is attached.
Okay, connecting the transistor output of the doorbell receiver to a relay might work, but I want more control over the time duration. So I figure a 555 timer circuit in a "oneshot" mode would work. I would be able to change the R/C network to be able to have an output time duration of anywhere from 0.1s to 30s.
The doorbell receiver is powered by two C cells (3V), and I would like to run the 555 timer circuit and relay off the same battery source. So, I purchased some low power (CMOS I guess?) TS555IN timer chips. I made a test circuit as seen by Tony van Roon here: http://www.uoguelph.ca/~antoon/circ/pulsetimer.html
It works fine, and I can tailor my output time duration by changing the resistor/capacitor network.
I then substituted transistor Q1 of Tony van Roon's circuit with the output transistor of the doorbell circuit in my test 555 timer breadboard. The RF doorbell receiver output indeed triggers my timer circuit, however, the duration of the R/C network in the timer circuit is apparently being overridden by the long duration trigger from the doorbell circuit. How do I make the output "unresponsive to long duration or repeated input triggers".
The allaboutcircuits chapter about monostable multivibrators says it's possible, but I don't know how.
One more issue: how do I get the timer circuit to NOT do an output when I apply power to the circuit?
Hopefully I've made myself clear. Any help is appreciated! Thanks!
Dave