I have a number of different power supplies, and one or more get used almost every time I test a new project or circuits shown in articles. If it does, you know you've made a mistake before it has the opportunity to damage the equipment with which it will be used. You can also test power supplies! A 15V regulator should show low output until the input reaches around 17V, and after that the output should not increase beyond 15V. Output voltage (for dual supply circuits) should all be close to zero volts, and if you have at least a couple of amps available, even low-volume tests can be done with power amps connected to a dummy load or a speaker. If testing audio equipment, you can verify that the circuit draws an appropriate amount of current (this depends on the circuitry), and doesn't misbehave when a suitable operating voltage is reached. one-tenth of the cell's capacity, say 250mA for a 2,500mA/h cell). For example, to charge a Li-Ion cell, you'd set the open-circuit voltage to 4.2V, and the current to perhaps 1/10 C (i.e. Once charged to a reasonable level, the voltage will remain stable and the current will fall as the battery approaches full charge. If the battery (or cell) is fully discharged, you limit the charge current to a safe value, so the supply's output voltage will fall, rising as the battery charges. I suggest that you also read Bench Supplies - Buy Or Build?, as there are some relevant points made, along with some more circuits to consider.Ī good supply is ideal for charging batteries, as you can set the maximum voltage and current independently. ![]() ![]() A very common requirement for power supplies is for battery charging, for lead-acid, nickel-cadmium, lithium or metal hydride cells and batteries. By increasing the voltage slowly, any fault will cause the current to rise very quickly after you reach a voltage that causes the fault to manifest itself. The inclusion of current limiting is especially handy, as you can set the limit low enough that it won't cause any damage (preferably less than 100mA). Ideally, a test supply will have a voltage range sufficient to handle everything from logic circuits up to power amplifiers, preamps, and any other electronic circuits that are either faulty, or have just been built. Part 1 - Voltage And Current RegulatorsĪpart from their use within equipment (which is the main topic here), regulated supplies are very handy pieces of test gear.
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