About RelayRepRap

This project is about exploring whether it is possible to make a RepRap control system that can be made by a RepRap.

Toggle circuit using 3D printed relays

Relay circuitsPosted by Will Stevens Sat, March 12, 2016 22:47:32
This video shows a toggle circuit made from 3D printed relays:

Here is the circuit diagram:

Here the downward pointing arrows represent 0V, the upward pointing arrows represent a voltage twice that required to activate a relay.

The toggle circuit failed fairly quickly (<100 operations) because relay C is switching the coil of relay A and this causes arcing at the normally open terminal of relay C which welds the contacts closed.

I found that this particular design of relay fails after a few 10,000s of operations even when switching non-inductive loads. Generally it fails by remaining closed after power is removed from the coil. I haven't yet worked out what the failure mode is, but some possibilities are:

- PLA creep, reducing the force that pushes the moving pole back to the normally closed contact.

- Magnetization of the coil nail, causing the pole to stick on the normally open contact.

- The pole nail become loose.