I figure a simple wrap-wires-around-a-bolt transformer should work for the job.
Nope. Google "Eddy currents". A big solid piece of iron isn't suitable for this. You'll just heat up the bolt really, really hot.
I've got NiChrome wire for the element, and I need a cheap way to step down 120V AC to about 50V AC @ 2.3A. (or 25V @ 4.6A or 17V * 6....
My guess-work assumption is that I need to make the primary coil with
enough turns so that its reactance will prevent the primary from
No. The leakage inductance will be what you get, it won't prevent an overcurrent.
What factor must I design to ensure that: 1) The transformer won't
burn itself up
You add a circuit protection breaker designed ...
You can remove the HV secondary of a microwave oven transformer and wind a secondary to use it for this purpose if you want. Roughly you'll need about 50 turns on the secondary (cut and try) for 50VAC (about 1V/turn so lower voltages may be easier to wind). The downside is that you'll need thicker wire for the higher current if you go lower in voltage.
The reactance will not be increased significantly by increasing the number of turns on the primary
A common way of making a transformer short-circuit proof is to reduce the coupling between primary and secondary to increase the leakage inductance. This may involve the way the laminations are arranged or even put the primary on a separate limb of the ...
The following circuit is one that I modified from Mosaic Industries.
simulate this circuit – Schematic created using CircuitLab
I used a relay in the schematic for ease of testing, but a switch should work equally well.
As per your specs, it starts in the "ON" state. The voltage is near 5V when on, and near ground otherwise. The current draw ...