Electronics > Beginners
I'm trying to emulate a fluid level sensor
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skyjumper:

--- Quote from: Rerouter on October 07, 2019, 05:41:44 am ---Your after a circuit like this, I use them for testing instrument clusters, ...

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Thank you! I'll study this.


--- Quote ---In reality you could use a constant current LED driver and PWM its dimming input, most gauges are 0.5-10mA, with the resistance range only depending on the coil used inside the gauge,

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The gauges that low current? I didn't realize this, I thought they just measured the current directly.

So then, a constant current LED driver? Great idea! This or something similar?

Diodes Incorporated AL5816Q

This is a 0 to 10ma out current controller that has PWM dimming capability...

https://www.mouser.com/datasheet/2/115/AL5816Q-1522395.pdf

Rerouter:
Probably best if you measure it first for the dimmer Idea, but for the modern cross coil gauges it tends to be full scale around 10mA, empty at 0.5, direction is influenced by how they wire the 2 coils internally, 1 coil is the bias (from supply to ground through a resistor), the other is the signal, with a lower current to rotate the pointer by 90 degrees,

but depending on the age could be an older thermal bimetallic gauge which where sometimes up to 50mA, with a few rare audi gauges burning up to 100mA through the signal pin (because I assume they enjoyed the smell of melted plastic)
Zero999:
The value of a digital potentiometer can be divided using an op-amp circuit.

What's your budget? A ready made solution exists, but it's not cheap, see link below.
https://www.kele.com/Catalog/24%20Transducers/PDFs/RES-1E%20Series%20Catalog%20Page.pdf

Check out the following thread:
https://www.eevblog.com/forum/projects/ptc-resistance-output-from-0-10v-analog-input/
skyjumper:

--- Quote from: Zero999 on October 07, 2019, 10:29:50 am ---The value of a digital potentiometer can be divided using an op-amp circuit.

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--- Quote ---What's your budget? A ready made solution exists, but it's not cheap, see link below.
https://www.kele.com/Catalog/24%20Transducers/PDFs/RES-1E%20Series%20Catalog%20Page.pdf

--- End quote ---

That looks cool! I need several for my boat and a friend wants a few for his.


--- Quote ---Check out the following thread:
https://www.eevblog.com/forum/projects/ptc-resistance-output-from-0-10v-analog-input/

--- End quote ---

Thanks!
KMoffett:
Since it's the current that actually determines the needle movement, could a simple voltage controlled current circuit work as an MCU controlled variable resistance?
https://daycounter.com/Circuits/Current-Servo/Current-Servo.phtml
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