Presented here is a Laboratory Power Supply with 0-30V voltage and 0-3A current regulation. The schematic is pretty straightforward, it uses standard dual opamps such as TL082, TL062, TL072, NE5532, RC4558 and MC34072. The trimmer P3 adjusts the minimum current limit. P4 adjusts the maximum output voltage. After the final adjustment you may replace the trimmers with standard resistors. Power transistor dissipates quite a bit of heat and thus require a heatsink with optional fan. We may use two or tree transistors in parallel with emitter resistors to achieve more power. The transformer must be 100-120W with 27-30VAC output voltage.
Build Accurate LC Meter and start making your own coils and inductors. This LC Meter allows to measure incredibly small inductances making it perfect tool for making all types of RF coils. LC Meter can measure inductances starting from 10nH - 1000nH, 1uH - 1000uH, 1mH - 100mH and capacitances from 0.1pF up to 900nF. The circuit includes an auto ranging and reset function to make sure the readings are as accurate as possible ... [more]