Electronics > Projects, Designs, and Technical Stuff

Amazing old school electromechanical ramp generator

(1/3) > >>

ChristofferB:
I've pulled this out of the scrap heap at my university! It's an "electromechanical sweep generator" no manufacturer. Might be Oxford.

It's a rather sleek 2U rack box that delivered the slow ramp for a set of coils to sweep the field of a 1970s superconducting magnet! Look how simple it's built (electrically)

A forward/reverse switch delivers power to a motor that through a huge gear reduction turns a 10 turn pot set up as a voltage divider, giving 0-5 V out over 1 min to 1000 min!

Astonishing

Unfortunately I cant get it working.. the voltage out is spot on( preset by 10 vernier knob) but no motor movement. I can't quite recognise the motor type either, it has 4 wires out.

The motor gets 24VAC when the thing is switched to forward or reverse so I'm afraid its the motor..

Taking apart the gear stacks are gonna be hell but I pray that it's just seized up with grease, and it can be fixed by exercising it.

Any ideas what else to try? I'd love to have this wierd thing functioning!

edit: I think this is a synchronous motor

 

Refrigerator:
For starters you could measure the resistance of the motor windings to check whether they're ok.
Also for a single phase motor to run it either needs a shaded pole or a start winding with a capacitor.
This looks like the latter so you might want to look at that as well.

ChristofferB:
Both windings measure ~1.3K, so the motor is probably good. It doesn't hum or buzz enough to feel or hear when it's in "run" position.
The limit switches (seen by the potentiometer) are ok too.

There is a cap between the two windings, perhaps it's fried.

Renate:

--- Quote from: ChristofferB on August 18, 2020, 07:30:18 pm ---Perhaps it's fried.
--- End quote ---
More likely dried?
That's a pretty standard bidirectional AC motor with two windings and a run capacitor forming a triangle.
Connect common and "A" to power it runs forward, connect common and "B" to power it runs backwards.

Doctorandus_P:
The motor kinda looks like a stepper motor to me.
Some stepper motors have their coils in that orientation.

 A (2 phase) Stepper motor ideally runs on sinusoidal voltages with a 90 degree phase difference, so mains voltage (frequency) can easily be used as a time reference with one or 2 capacitors to get your phase shifts right.

If your motor windings are 1.3kOhm, then your motor likely runs directly from mains voltage.

Navigation

[0] Message Index

[#] Next page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod