555 Timer? Input sawtooth 0-8 volts, Output pulse variable duration

[gmcjetpilot]

This is what I want to do.

Input: sawtooth from 0-8 volts with freq of 30 Hz to 60 Hz

Output: a pulse when input is at a user set voltage between 1-7 volts.

The pulse output is adjustable voltage (3-9v) and duration (5uS to 2mS)

I'm flexible, it is not super critical. I just need a stable trigger even if it has some delay.

If some one can draw out a circuit I would appreciate it.
The 555 timer seems to be the way to go?

Thanks

 

[MacGyverS2000]

Plenty of online Java stuff that will calculate every value needed for 555-based component projects... Google is your friend for this one.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[gmcjetpilot]

Thanks MacGyverS2000, I assume you are talking microcontrollers. I did not consider that. I wad hoping to do it was a handful of discrete component, comparator IC's and so on. However if you have some simple Micocontrollers let me know... pixaxe-08 is something to look at.

 

[VEBill]

First a comparator to set the trigger point. You'll need a reference voltage and a potentiometer to adjust the trigger amplitude.

Then a one-shot to make the pulse. Adjustable duration with another knob.

Then an adjustable voltage divider (potentiometer) to tweak the amplitude.

Be careful with defining your requirements. A sawtooth waveform goes up AND down. So you might get a double pulse, which is fine if that's what you want.

I don't think you can do all this with a single 555, but perhaps there's a clever trick that makes it barely possible. But it's probably easier to just make the straightforward (step by step) version.

All these building blocks are on the Internet.

 

[fsmyth]

There are a few example circuits at:

http://hmin.tripod.com/als/fsmyth/pages/555apps.html

Dig around. There might be something that matches
your application.
<als>

 

[DCLabs]

Here is an untested circuit. It should work. Might need some tweeking and bypass caps.

Dean Cooper
dclabseng.com