What is this

[snowmix]

I got this today at an estate sale for a dollar. I am new to electronics but to me it looks like a high voltage power supply or something.

[divelectservices]

It looks to me like the power supply for an alarm system. 

[BurningTantalum]

It's part of a Sunbeam breadmaker... Oh, wait..!

[SL4P]

I'd guess some sort of heater or large light (dimmer) controller.
Those look like BIG triacs on the heatsink...

[SeanB]

DC motor speed control, that is a SCR on the heatsink. Used for a large ( up to 2HP) DC motor run off the rectified AC mains, probably one with separate field and rotor connections.

[Kleinstein]

From the terminals marked Bat- and Bat +, this looks like a batterie charger. Likely low voltage and something like 10 amps.

[Kalvin]

Tesla motor control circuitry. First gen.

[dom0]

From the terminals marked Bat- and Bat +, this looks like a batterie charger. Likely low voltage and something like 10 amps.

Maybe a supply/charger for a small alarm system or some small emergency light installation.

[codeboy2k]

Could be a heater supply for a homemade moonshine still.   Speed control is for the automated stirrer.

[snowmix]

The old man that who's estate sale it was just said ill figure it out  when I asked him what it was. I don't know if he forgot or it was or was just upset to have to move to a retirement home. He was an electronics professor at metro state for years he said. I found tons of kits in plastic bags that were never opened and the PCB on this thing looks similar to those ones.  Here is a shot of the PCB. If anyone knows how I could start testing to see what this thing does let me know.

[TerraHertz]

In the 1st pic, on the left are AC mains in and 4-wire connection to a battery. On the right, a bunch of connections that seem like they might be status and DC output voltage.

On the heatsink, the SCR snubber RC network is referenced to the body of the heatsink, which is probably 'Batt+' or close to it. If it was mains live, those warning signs would mention that much greater danger.
So the SCR is not in the mains side of the circuit, therefore must be involved in the output. It can't be a crowbar protection circuit since you don't put snubbers on those, nor do you crowbar a large battery. So I think it's switching the LV rectified secondary side of the transformer.
Also there doesn't seem to be any large electro, and I don't see a series pass transistor on the heatsink, both of which you'd expect on a regulated DC supply.

I'm guessing it's a charger/management unit for a large lead-acid battery. Two 741 op-amps is about the right complexity for that task.
It monitors the battery voltage, and if low, just dumps current into it via the SCR acting as a phase controller on raw fullwave rectified AC, via a split secondary winding and the two big diodes on the heatsink.

Edit: Like this. (Oh, plus that big power resistor in series with the charging line to the battery.)

[calexanian]

Well thats the fabled 41629 obviously. It made the Kessel Run in less than 12 parsecs!  O0