Hello,

Would anyone suggest a circuit for a PWM around a 556 timer that:

• near full range duty cycle (~0% - ~100%) can be controlled by a varying 0v-5v signal
• a way to adjust/calibrate input voltage vs. duty cycle (i.e. 1v = 20% duty or adjust it to 1v = 35% duty)
• ~20Hz
• the output would be using the 'on/high' part of the wave to ground a 12v to actuate a solenoid (factory boost controller for car).

The voltage supplied to the circuit would be regulated by the car's ECU at 5v.

Thanks,
Rey

 

the 12V solenid is not problem
you can connect a FET or BJT with the digital controller output, and connect the solenoid with it on high or low side.

 

Hi Rey,

I am looking for a similar circuit to convert a 0V to 5V (Airflow sensor output) to Duty Cycle / PWM.

Any suggestions or links?

Paul.

 

Hi Rey,

I am looking for a similar circuit to convert a 0V to 5V (Airflow sensor output) to Duty Cycle / PWM.

Any suggestions or links?

Paul.

http://www.allaboutcircuits.com/vol_6/chpt_6/9.html

This is what I'm starting with.

 

Voltage to PWM , just an outline, but it works fine on my electric tractor. Best if 100k was a pot so ramp = 5v @ 50 msec. 556 out limited to 200 mA sink.

 

Is this MOSFET OK to use for this application?

http://www.nteinc.com/specs/10to99/pdf/nte66.pdf

Again, 5v to gate to turn on/off to run a 11-14v solenoid @ 20 - 40 Hz.

The solenoid currently is powered thru a 10A fuse along with 2 other solenoids. So, it shouldn't draw more than 10A.

Thanks,
Rey

 

Why are you running a solenoid at 40Hz? That's pretty fast for a mechanical solenoid and it may simply just stay on or off.

 

more than likely 15 - 20 Hz. varying duty.

 

How big is the solenoid?

 

I just verified that the solenoid is driven with a 22Hz PWM from the ECU. It's a WG/boost control solenoid for VW/Audi (N75).

 

Voltage to PWM , just an outline, but it works fine on my electric tractor. Best if 100k was a pot so ramp = 5v @ 50 msec. 556 out limited to 200 mA sink.

Bernard, are you generating a 20Hz triangle or sawtooth wave with the 556 on the right, then comparing it to the 0-5v from pot on lower left to produce a square wave with desired duty? If so, why is it going back into another 556?

I'd like more info on your circuit.

Thanks,
Rey

 

Is this MOSFET OK to use for this application?

http://www.nteinc.com/specs/10to99/pdf/nte66.pdf

Again, 5v to gate to turn on/off to run a 11-14v solenoid @ 20 - 40 Hz.

The solenoid currently is powered thru a 10A fuse along with 2 other solenoids. So, it shouldn't draw more than 10A.

No, you would need a logic level MOSFET. The NTE66 is a standard power MOSFET. You pay quite a bit extra for the NTE convenience vs the prices you pay for the manufacturer parts. NTE doesn't actually make their own components. You can cross-reference other manufacturer's part numbers to NTE parts, but their cross-reference doesn't go the other way.
The NTE66 is equivalent to an IRF530.
A logic-level equivalent is an IRL530.
Usually, you want to use at least double the actual current capacity rating.
Without knowing more about the requirements, an IRLZ24N, IRLZ34, IRLZ44 should be in the range of what you need.

 

I ended up buying one of these: http://www.nteinc.com/specs/2900to2999/pdf/nte2987.pdf

There is a Fry's local to me that carries NTE.