Very handy and simple timer circuit, using a 555 timer and 4 more parts.
I am incorporating this into my serial port drive, to ignore the flashing outputs until PC has had time to boot up.
Im using 5 volts for the supply, but I think it can go up to 17 volts. (Check specs on your timer to find out for sure.
The electrolytic capacitor will have to be selected by voltage too, good rule of thumb is at least 1.5 times the supply voltage.
I used a 220 uf 10 VDC elec. capacitor.
For Ra I used a 47K resistor in series with a 500K pot, so I could adjust the time. Time range is around 16 seconds to a little over 2 minutes.)
I will post the complete drive circuit when I am finished with it.
How it works:
When power is applied, pin 3 is low, or connected to ground.
The capacitor (C) charges through Ra. When voltage on pins 2 and 6 reach 2/3 of power voltage, pin 3 goes HIGH (+)
When power is removed, the capacitor discharges through the 1N4148 diode. (Quicker reset than it would be if it only had Ra to discharge through.) And pin 3 goes low.
I sent the guy that owns the website an email asking him for permission to use this, but email was returned as un deliverable.
If anyone objects to me using this, please let me know and I will remove it ASAP.
Here is a link to the site, it also has a handy calculator that allows you to choose the proper values for C and Ra, based on the time delay you need.http://clarkson63.uk/555-timer/operation/frames3.html