I've acquired an old VARIAC and am checking it out for functionality.
It appears to be 110v IN with a 12,0,12 secondary for the motor drive controller. In the no.2 image there are the chopped off wires that seem to be a fixed 110v isolated secondary - you can see the 0 & 110 markings. Continuity testing and live measurements support all this.
Does that seem normal for a VARIAC to support this configuration? I'm a little surprised. My other VARIAC is...just a VARIAC.
2nd question: I'm in a 240v world so IF this was manufactured for 110v use would it present any problem to use it at 240v IN? I realise the 12,0,12 will be double the voltage (yes I can't directly use it for the motor board) and the fixed 110v will be a fixed 240v. And the current rating at 240v would be halved. But is there a design aspect that means it would be unwise to use this as a 240v VARIAC if intended for 110v?
Appreciate any experienced views out there.
Cheers,
Steve
It appears to be 110v IN with a 12,0,12 secondary for the motor drive controller. In the no.2 image there are the chopped off wires that seem to be a fixed 110v isolated secondary - you can see the 0 & 110 markings. Continuity testing and live measurements support all this.
Does that seem normal for a VARIAC to support this configuration? I'm a little surprised. My other VARIAC is...just a VARIAC.
2nd question: I'm in a 240v world so IF this was manufactured for 110v use would it present any problem to use it at 240v IN? I realise the 12,0,12 will be double the voltage (yes I can't directly use it for the motor board) and the fixed 110v will be a fixed 240v. And the current rating at 240v would be halved. But is there a design aspect that means it would be unwise to use this as a 240v VARIAC if intended for 110v?
Appreciate any experienced views out there.
Cheers,
Steve
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Putting 240V on a 110V transformer is not a good idea! It will quickly overheat and burn out.
Most, if not all, Variacs are not isolated. This could be just a variable transformer. Are the brushes OK?
Most, if not all, Variacs are not isolated. This could be just a variable transformer. Are the brushes OK?
Understood re 110/240v. The brush & rotor arm is in very good condition despite it being a fairly old and well used device.
I do find those other connections intriguing. I've tested the continuity of those 0 & 110 chopped wires and they are certainly not connected to the primary and provide approx 110v when fed with 110v - those voltages do differ slightly hence I'm fairly convinced it's a 1:1 [isolated] secondary.
With motor control for the rotor I was hoping to remount it all in a case and use it but the 110v isn't of great use to me but I dislike throwing stuff out. The motor board and how it operates is taking some thinking how it works at the moment. The schematic isn't complete yet. The board isn't in great shape but it actually all works and the 741 balances out with the pot adjustment (not yet documented). Just got to figure out how the user control worked to vary the required voltage. Fun project.
I do find those other connections intriguing. I've tested the continuity of those 0 & 110 chopped wires and they are certainly not connected to the primary and provide approx 110v when fed with 110v - those voltages do differ slightly hence I'm fairly convinced it's a 1:1 [isolated] secondary.
With motor control for the rotor I was hoping to remount it all in a case and use it but the 110v isn't of great use to me but I dislike throwing stuff out. The motor board and how it operates is taking some thinking how it works at the moment. The schematic isn't complete yet. The board isn't in great shape but it actually all works and the 741 balances out with the pot adjustment (not yet documented). Just got to figure out how the user control worked to vary the required voltage. Fun project.
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