millisecond timer

Thread Starter

gremlin

Joined Jul 22, 2010
19
has anyone got a simple circuit for a delay on timer to switch a optocoupler on with an ajustable delay from sao .001 sec to maybe 1 sec

any thoughts would be greatfully recieved

thanks

gremlin
 

Thread Starter

gremlin

Joined Jul 22, 2010
19
hi i can use any supply voltage so long as it will triger a optoisolator i would like to use 9v from a AA battery pack but could go to 12v if needed
the idea is to trigger a TIP120 transistor via the optoisolator

the timing delay i was hoping to use a pottentiometer maybe two one caurse one fine ajustment

i have had a quick look at some 555 circuites on the net and this great site but canot find any with millisecond delay

thank you

gremlin
 

SgtWookie

Joined Jul 17, 2007
22,220
Something like the attached should work for you.

It has a range a bit wider than you specified, but that's necessary due to tolerances in resistors/capacitors.

I didn't show caps across the Vcc/GND terminals of the 555 timer; but you need an 0.1uF/100nF ceramic or poly metal film and a 1uF or larger aluminum electrolytic.
 

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Thread Starter

gremlin

Joined Jul 22, 2010
19
many thanks sgtwookie for your time and help i will give that a go tommorow on some breadboard

one thing i forgot to say was that it will be trigered by a microphone so a single pulse for a millisecond or so when it hears a bang
then wait the pre set time and fire a 12v dc solenoid via the tip120 transistor it would be nice too for it to only fire once untill a reset button is pressed, the mic will have a simple pre amp so the threshold can be ajusted

thank you again

regards

gremlin
 
Last edited:

SgtWookie

Joined Jul 17, 2007
22,220
Oh, silly me - I thought you wanted an astable instead of a monostable. That's a different circuit, but it'll have similarities. I really don't know why I posted an astable configuration.

Do you have the preamp for the mic built already, and is it working?
 

Thread Starter

gremlin

Joined Jul 22, 2010
19
hi no i dont have the pre amp done as yet but i have a simple circuit to copy from a vellerman mono pre amp kit
thank you once again

gremlin
 

Thread Starter

gremlin

Joined Jul 22, 2010
19
hi sgtwookie yes i managed to see the 741 from the pic on the supliers website,
i dont mind that it is crude and requires 9+ volts as i have 12v available from the battery pack i am going to use on the solenoid,
it does not matter as i am only looking to get a response from a microphone detecting a bang from a droped item etc so no real audio application is required,

i was hoping that someone may have a simple circuit etc as i was looking at having to use a arduino micro to do what i wanted , but did not want all the addition of the periferals to run the arduino crystals etc etc
i was hoping for same simple 2 or three chips and some capacitors resistors etc

thank you for your kind assistance

regards

gremlin
 

SgtWookie

Joined Jul 17, 2007
22,220
After the delay time is elapsed, how long do you want the TIP120 transistor turned on?

If it's a relay or solenoid, it will take a LONG time to respond. You would likely have to have it on for at least 100mS.
 
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