Hi, Im working on a pulse tig device which works by hijacking the foot pedal i have attached an images of the insides of the pedal and i'm looking for advice on how i could achieve this with a digital pot. Or if anyone has any other suggestions id be happy to hear them!. Thanks.
I can't tell much from the pictures. Do you know the value of the pot (ohms) and the voltage across it?
Digital pots tend to come in a limited range of values, and they are usually rated for low voltage.
I believe there are 3 common kinds of digital pot interfaces -
I2C
Parallel
Up/Down
Up/Down is easy, but it may not be appropriate for your application (it's good for a volume control or temperature control).
Parallel is easy (as long as you understand digital data) but it requires 8 pins for 8 bits.
I2C is easy with a library.
A through-hole package will be easier to wire-up than a surface mount part, but there are fewer through-hole part choices.
The ohms is 25k im a little unsure on the operating voltage purely due to its a bit tricky to measure while operating however i do know the cable is rated for 125v at 5amps if that helps?
Also here is some info on the pot
Tolerance ±10%
Residual resistance max. 2Ω
Input voltage max. 350V AC
Power rating 0.25W
Dielectric strength 1500V AC
Insulation resistance min. 1000MΩ
Rotational life 1,000,000 cycles
Operating temperature range –55°C to +125°C
No, that doesn't help at all.
We need to know the maximum voltage that might ever be across that pot. This will require measurements, or a thorough analysis of the circuit to which the pot is connected.
If it's more than 36v, that's a problem - I think that's the highest that digipots go (microchip's high voltage line, just came out in the past couple of years ). I think there are a few more options at 12v, and oodles of options if it stays under 5v.
Could you use a servo to move the foot pedal under Arduino control?
...R
Yea i thought about a servo but its just to slow. I'm going to hook up my meter tomorrow and measure the voltage across the pins pretty sure its just a control voltage (hopefully). If however its a high voltage pot are they any methods i could use to control it digitally?
recox99:
Yea i thought about a servo but its just to slow.
Slower than a foot?
...R
I've measured the pins and voltage is 30vac. Not slower than a foot but i plan to make it do about 3 pulses a second.