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First of all, i must say that I am a software engineer, with very-low to no experience in circuits designs, and a very rudimentary understanding of electrical engineering and circuits. 101 really.

For a software project I am playing with I have built a small physical gauge simulator using some ready-made cheap 7-LED and old needle voltage and amp gauges. They are all powered from a standard DC 24v 3A power supply and I am using a potentiiometer to make the values change manually when i need to change them.

My challenge is the following : Is there a simple way, without special components / devices (NOR MCU arduino/pi to make the gauges "jump" automatically and basically mimic the operation of me fiddling with thee potentiate ? Basically some kind of a DC oscillator - but random jumps are ok.

I do not have an the option (time-wise) to buy special components but I do have a lot of standard ones, ranging from capacitors, to resistors, DC power converters, diodes, LED's, Fuses, transistors (PNP,NPN, mosfet), coils, magnets photoresistors, humidity sensors etc. On the device level I have some low-voltage motors, steppers and solenoids. There is a bit of everything in the very-basic range of stuff.

Is there a simple circuit that can help me achieve this "jump" in the power without any code ? ( funny question for a coder - I know. but there IS a logic behind the project :- )

EDIT I : Here is a picture for better understanding .

enter image description here

EDIT II :

I ended up using a combination of 2 solutions :

A - I took a solenoid that was producing heat and connected it to a relay via and NTC ( PTC would work the same I assume ). The NTC got heaat from the solenoid and functioned like a "gate" for the relay, which also started a small fan to cool the solenoid again. The solenoid operation also made the amp jumps .

B - I Friend brought me an ne555 which I connected to relay. ( but that's an oscillator - which was a few days later )

Although these primitive methods work, I would still like to hear other advice on how to achieve that in some other way .

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  • \$\begingroup\$ So basically you want to have a random signal being fed to the gauges? And the question is how to generate this signal without code, just with analogue electronics? \$\endgroup\$
    – anrieff
    Commented Oct 26, 2018 at 10:59
  • \$\begingroup\$ Have you considered adding random numbers to the measured data in software? Or is this solution too simple and elegant? \$\endgroup\$
    – Harry Svensson
    Commented Oct 26, 2018 at 11:00
  • \$\begingroup\$ @anrieff - yes, I think this is basically it .. the signal being any range that my power supply can generate ( preferably above 5v ) \$\endgroup\$
    – Obmerk Kronen
    Commented Oct 26, 2018 at 11:10
  • \$\begingroup\$ @Harry Svensson - how would this help changing the gauges display ? \$\endgroup\$
    – Obmerk Kronen
    Commented Oct 26, 2018 at 11:12
  • \$\begingroup\$ @ObmerkKronen Not sure, I was thinking about "Simple way to create a disturbance on DC power". \$\endgroup\$
    – Harry Svensson
    Commented Oct 26, 2018 at 11:26

1 Answer 1

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To me, the simplest option would be a simple 2-transistor oscillator, as illustrated in this answer.

Choose resistor and capacitor values that give a sufficiently slow oscillation.

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  • \$\begingroup\$ Thanks, I actually tried this method and it works like a charm . \$\endgroup\$
    – Obmerk Kronen
    Commented Nov 13, 2018 at 9:07

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