I’m looking for a bit of advice, I’m trying to create a basic robot arm where servos are controlled by variable resistors however the resistors are giving erratic outputs.
I started with the resistor pushed into a breadboard with +5 one end and ground the other with the middle pin to an analog pin. If I apply a lot of pressure on the resistor to press it into the breadboard it is fairly reliable but often it will suddenly start giving random values causing the servo to quickly spin the full 180°. I assumed this was due to poor electrical contact.
To try and fix this I used an arduino nano and soldered the whole circuit together removing the potential issue of contacts, however this made the issue even worse! Sometimes the resistor works accurately, other times it starts going crazy.
I’m thinking the resistors are broken, or it’s some sort of interference in the wires. Has anyone experienced this?
I’m looking for a bit of advice, I’m trying to create a basic robot arm where servos are controlled by variable resistors however the resistors are giving erratic outputs.
I started with the resistor pushed into a breadboard with +5 one end and ground the other with the middle pin to an analog pin. If I apply a lot of pressure on the resistor to press it into the breadboard it is fairly reliable but often it will suddenly start giving random values causing the servo to quickly spin the full 180°. I assumed this was due to poor electrical contact.
To try and fix this I used an arduino nano and soldered the whole circuit together removing the potential issue of contacts, however this made the issue even worse! Sometimes the resistor works accurately, other times it starts going crazy.
I’m thinking the resistors are broken, or it’s some sort of interference in the wires. Has anyone experienced this?
Thanks
I think the word you are looking for is "potentiometer". That means an adjustable potential or voltage source.
They are not designed to carry very much current. Since you haven't told us the resistance value of your potentiometer, I can only relate your problems to sending too much current through your potentiometer.
A schematic of your setup would help a lot to reach a proper conclusion.
Some potentiometers are noisy, because the wiper does not make good contact with the resistive element, due to dirt, burning or oxidation of the wiper or element. Try a different one, preferably from a different manufacturer.
For this sort of thing, you absolutely want one with a "moulded carbon" track. These have a little carbon brush held in the wiper as it moves over the track that is embedded in the ceramic body of the potentiometer.
Alternatively a "cermet" type. Not sure what they use in servos - which is what you are describing - but it would not want to be like the common cheap volume control.
It is pretty obvious that it needs to be solidly mounted and soldered connection, not on a breadboard.
Forcing a pot into a breadboard like this stretches the breadboard contact springs and leaves them slack and unreliable. Solder some hookup wires to the pot and then use those. However there are some pots with narrow pins that are breadboard-compatible, they are not the commonest sort. You can also solder header strips to the pot, using pins 1,3,5 of a strip of 5 contacts.
There will also be break-out boards available with headers already fitted.
