How can I make the current adjustable?

Hi, I have a 240VAC supply coupled to a 2amp variac supplying power to a 240VAC/22V 7amp Toroid transformer. This then goes to a 50amp bridge rectifier. Obviously I can adjust the voltage via the variac but would like to be able to adjust the current also for hobby electroplating. How can I do this simply? I do have a few transistors etc that are on a redundant (faulty) amplifier. A simple schematic would be nice! Thanks in advance. P.S Please keep the answers simple.How can I make the current adjustable?If you want %26quot;constant%26quot; current it needs a current regulator. If it is just adjustable current, you only need the Variac. The current is proportional to the voltage in most plating baths. However you may need a fixed current limiter like a lamp or resistor of suitable resistance and power. The second link shows a switched bank of lights, which allows adjustable current in fixed voltage supplies like a battery o battery charger.



Make sure the primary or secondary of the transformer is correctly fused to protect against shorts.



Another simple approach is to pulse the supply on and off. The pulse duration can be seconds. The ratio of on to off gives the average current. This is simple enough to implement using a 555 timer (or other electronics or even a microprocessor to generate the pulses at the desired rates. The pulse generator is used to operate a relay or an electronic switch using transistors or a power MOSFET device.



A current regulator uses a similar idea called pulse width modulation, but at a higher rate, and using a feedback system to regulate the measured current. There are also linear regulators, the equivalent of a resistor that varies automatically to regulate the current. The dissipation is high in this case, so these are not very suitable. Look up %26quot;switch mode current regulator%26quot;. These are basically voltage regulators modified to regulate current. It is easier to use an integrated circuit to simplify the design. See the link.How can I make the current adjustable?The out put 22Volt side connect a Series 0- 10 ohms,10amps rheostat or ( variable strip Resistor) and adjust the current or connect some Auto head lamps as a resistor (series parallel) %26amp; adjust your current.(Better to use 240/12V 15amps Transformer for bit higher current)