Help needed with On/Off/On Circuit

[dwhildre]

The other day I posted a question about how to make a simple npn switch, that would take a 12+ and make the switch to ground who's current would be no above 10mA.

I have found that my needs are not of a single switch but a "pulse" of ON/OFF and back ON. Making the ground circuit, then breaking it, and then making the ground again. Hope this makes sense. Very new to electronics here, but I like to learn and do learn fast.

My initial though would be the use of and NPN to a PNP than back to a NPN using maybe a small capacitor in each to slow the signal just a hair so all isn't switched in a micro second. Shouldn't need a lot of time between switches but very small pause the total of which may not exceed a second in time. But that is just me trying to make and uneducated guess here; but trying to learn.

Thanks to anyone who can give me a hand.

 

[barry]

Slow down, there.

You need something to generate a pulse that will turn your NPN on and off. There are many ways to do this. What are the on/off times you require? Are you supplying a trigger to start the on-off-on sequence? Can you give us a little more information about your application?

 

[vinoth8051]

Hi dwhildre,
You have to design monostable multivibrator. You have almost made the guess. Check the pictures https://www.google.co.in/search?q=m...gKtHhrAfzk4CgBg&ved=0CEgQsAQ&biw=1366&bih=634.
Hope this helps...

 

[dwhildre]

Thanks.

Yes i do have a trigger of 12+ vdc.
The timing of things is if one had a spst switch and turned it on, then off, and again turn it back on. 1 to 1.5 seconds for total circuit timing. Maybe .5 seconds per switch.
I looked and tried to understand and draw the circuit along with parts. Below is that drawing attached. If someone would like to check it and see if this will work, open for options and suggestions.....please

Again thank you all very much!