voltage controlled PWM help

[kaido]

Hi guys, I need a fairly simple circuit, but havent been able to find anything suitable on the net.

I want to control a 12v water pump via PWM, that increases with a 5v signal,

I would like the following options:

able to set (using a pot) what voltage (0-5v) that the pump turns on...
and able to set what voltage (0-5v) that the pump reaches 100% duty...

if anyone could help me out or point me in the right direction it would be much appreciated..

thankyou.

 

[dieplz]

I'm not quite sure if I completely understand what you are trying to do, but I did something pretty similar actually once before. I was controlling a pump's speed based on the output of a 0-10VDC transducer. Based on the output, the pump speed was determined by an AD654 chip, which is a Voltage-to-Frequency converter. Try taking a look at that chip. Hope this helps.

 

[Boncuk]

Hi kaido,

you don't require to use 0 to 5V to vary the duty cycle of the circuit. Using variable input voltage requires a pot anyway.

This is contained in the timer circuit already.

Boncuk

 

[samphantom]

PWM controlled by voltage

Hello guys

I was looking for something similar to this circuit, but my idea is to implement a circuit that increases the brightness of a led by increasing the voltage softly until reach the total bightness and then for a specific time of timer to decrease the brightness and stays ON only at 25% of brightness.

I try to incorporate a 555 for the timer and at the output a capacitor/resistor delay for ON time that increases slowly at 12v (which is the arrangement of leds) this output is going to the input of a PWM to increase the brightness with 95% duty cycle (which is the total brightness of led in my case) and then after timer goes off then the circuit delay softly decreases the voltage thus the PWM will decrease the brightness of led and keeping it at 25%.

Sounds a little bit complicated and I think the last part that keeps the PWM at 25% duty cyle is my challenge.

Does anyone know how to implement this part? or have some path where to illuminate myself?

Thanks everyone.

 

[kaido]

hey guys,been overseas and totally forgot about this but yeah. looks like the AD654 is what im looking for! thanks dieplz!

 

[pcbheaven.com]

**broken link removed**

I think is what you ask