Opto-isolater on pin
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Posts: 46,084
I have a small problem and would like some help.
I have a PWM valve controller board that uses a stamp to control the current
to a valve upto 1.3A @12VDC.
I do this by using a DAC to send an analog voltage to a DRV101 PWM
controller and then a high current FET.
The problem is I use a stamp pin to pulse the input of the DRV(in
combination with the DAC signal) to create a dither frequency of 150hz.
There is a 1k resistor inbetween the input of the DRV and the stamp pin and
the max value of the input to the DRV is 3.7V.
Once I pulse the pin, I return it to an input pin so it is effectively out
of the circuit and not affecting the analog voltage to the DRV.
Question (finally) is can I use an opto isolator in a way to simulate the
operation. I have a few stamps failing and this is the ONLY pin that is not
protected well and 'might' be a problem. I cannot have the output of the
isolator being pulled high or low continuously, so that is where I need the
help.
If anyone needs more info, I will gladly provide.
Thanks,
Mark
I have a PWM valve controller board that uses a stamp to control the current
to a valve upto 1.3A @12VDC.
I do this by using a DAC to send an analog voltage to a DRV101 PWM
controller and then a high current FET.
The problem is I use a stamp pin to pulse the input of the DRV(in
combination with the DAC signal) to create a dither frequency of 150hz.
There is a 1k resistor inbetween the input of the DRV and the stamp pin and
the max value of the input to the DRV is 3.7V.
Once I pulse the pin, I return it to an input pin so it is effectively out
of the circuit and not affecting the analog voltage to the DRV.
Question (finally) is can I use an opto isolator in a way to simulate the
operation. I have a few stamps failing and this is the ONLY pin that is not
protected well and 'might' be a problem. I cannot have the output of the
isolator being pulled high or low continuously, so that is where I need the
help.
If anyone needs more info, I will gladly provide.
Thanks,
Mark
Comments
controlled solenoid valve right now and would be interested in any info you
might have.
Basically, I have to measure a small pressure and use PWM to increase or
decrease the flow and keep it all pretty accurate. I need to have an
adjustable gain and setpoint. Pressure will be measured in 'inches of water
column'.
Original Message
From: "Mark Adams" <madams@a...>
To: <basicstamps@yahoogroups.com>
Sent: Thursday, October 02, 2003 7:45 AM
Subject: [noparse][[/noparse]basicstamps] Opto-isolater on pin
> I have a small problem and would like some help.
>
> I have a PWM valve controller board that uses a stamp to control the
current
> to a valve upto 1.3A @12VDC.
>
> I do this by using a DAC to send an analog voltage to a DRV101 PWM
> controller and then a high current FET.
>
> The problem is I use a stamp pin to pulse the input of the DRV(in
> combination with the DAC signal) to create a dither frequency of 150hz.
> There is a 1k resistor inbetween the input of the DRV and the stamp pin
and
> the max value of the input to the DRV is 3.7V.
>
> Once I pulse the pin, I return it to an input pin so it is effectively out
> of the circuit and not affecting the analog voltage to the DRV.
>
> Question (finally) is can I use an opto isolator in a way to simulate the
> operation. I have a few stamps failing and this is the ONLY pin that is
not
> protected well and 'might' be a problem. I cannot have the output of the
> isolator being pulled high or low continuously, so that is where I need
the
> help.
>
> If anyone needs more info, I will gladly provide.
>
> Thanks,
>
> Mark
>
>
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