Hi,

I have very little experience in electronic circuits and could use some help with my project.

I have a device (shutter) such that:
If I apply a voltage, then break circuit it stays 'on'.
It only turns 'off' when I ground the circuit.

What I have so far is a function generator with a transistor & device such that:
When a pulse comes in, the device is switched on for the duration of the pulse, and off when no pulse. It's the classic NPN transistor + load circuit.


What I need is: Some sort of logic device/circuit (I have no experience in this) where the first pulse turns on the device and the 2nd pulse grounds the device and turns it off. (something like, 1 --> 1, 1 + 1 -->0 switch).
Can anyone help? (and quickly)

 

Or maybe the first pulse quickly closes the circuit with applied voltage --> device on
2nd pulse closes the 2nd circuit with groune -->Device off

Ideas?

 

Why is this an "urgent" problem?

Unless it's going to fix the oil leak in the Gulf of Mexico, it's not very urgent.

 

Unless it's going to fix the oil leak in the Gulf of Mexico, it's not very urgent.

Even that won't be urgent if you get the government involved.

 

Even that won't be urgent if you get the government involved.

This is not a political forum.

That is why I like it.

 

I know, but I couldn't help myself after watching too much "truthers and 911 conspiracies" and people complaining the government needs to do more with the gulf oil problem.

 

What are the volts and amps you are going to be working with?

 

Quite low. Expect peak voltages to be 20 to 25V and at most 100mA (maybe 200mA).
Currently I have two TTL signals going in either the first or second inputs.
One is to apply voltage, other is to ground. It'd be great if I can make the circuit with only one TTL input
and there's some logic that switches back and forth.

 

I couldn't resist the earlier nonsense. You wouldn't believe how often people post "URGENT!" requests that aren't urgent at all.

Lack of planning on someone elses' part does not constitute an urgency on my part.

Anyway, you might consider using a D-type flip-flop with it's Q\ output connected to its' D input, and clocked by your TTL source. The Q output will then alternate between high and low.

You can pulse the set or reset inputs to achieve a known state for initialization, or monitor the Q or Q\ outputs and clock until you like what you see.