I need help to design a circuit to control a latching solenoid

I have an on/off foot paddle I want to connect to latching solenoid. When I press the peddle, I need to send a 100ms pulse to the solenoid. As long as I keep the foot down pressing on the peddle, nothing should change. When I take my foot of, I need to send another 100ms pulse. The solenoid will open when it get a positive 6VDC pulse and will close when getting a negative (-)6VDC pulse.

I don't really know how to start, but I know I don't want to use a microcontroller and I think a 555 timer can do the trick.

szangvil: I don't want to use a microcontroller

So why are you posting in Arduino forums? :)

Use a h-bridge to drive your solenoide and a 555 as a monostable to generate the pulse. The pulse should do two things, enable the h-bridge and trigger a flip flop. The output of the flip flop should drive the h-bridge direction.

But how do I keep it from generating pulses when the pedal is kept pressed?

Maybe start here?

http://www.instructables.com/id/Make-an-LED-Blaster/step2/Build-the-555-ic-one-shot-timer/

szangvil: But how do I keep it from generating pulses when the pedal is kept pressed?

All this would be easy with a microcontroller, but noooo.... ]:)

szangvil: But how do I keep it from generating pulses when the pedal is kept pressed?

You wire the 555 up as a monostable, then you AC couple into it from your foot switch (attach it through a capacitor) then you will only get spikes that trigger the monostable when you press and again when you release.

AC couple?

szangvil: AC couple?

http://en.wikipedia.org/wiki/Capacitive_coupling

Using a micro controller will take all the fun out of it ;-)

Fun... Hell man what you are talking about is hard work, the controller is easy

Bob

It might be easy but if I want to make many of these circuits, it means I have to prepare an ISCP connector on my PCB and upload a sketch to each unit, which is time consuming. I need it to be as small as possible since it needs to fit inside a foot pedal.

szangvil: It might be easy but if I want to make many of these circuits, it means I have to prepare an ISCP connector on my PCB and upload a sketch to each unit, which is time consuming.

a) Soldering a dozen extra components to a PCB is time consuming, too...

b) https://www.adafruit.com/products/394

In the long run, an assembly house would do that for me.

I really liked the pogo pins! Didn’t know this solution existed :slight_smile:

szangvil: In the long run, an assembly house would do that for me.

If you're producing on that scale then the cost of the parts/fabrication should be #1 priority. I'm not sure which would win though, you're only dealing with switches and digital signals so a microcontroller is hard to beat. Atmel makes some really, really small chips for simple jobs like this (six pins).

Goal is to make a couple hundred units. I will look into a simple cheap micro controller due to a much lower parts count.