With Instructables you can share what you make with the world, and tap into an ever-growing community of creative experts.
Tell us about yourself!
That bridge rectifier and capacitor are overkill just to power an LED. Just use a 400V or higher non-polarized capacitor in series with the LED, and since it's a Diode itself, it will rectify to 30Hz (or 25Hz) pulsed DC. Capacitive reactance is useful here. Reactance = 1/(2*pi*frequency*Capacitance). (340V peak - 1.8V LED) / 0.005A = ~68k resistor. 47nF nonpolar will do (for 240V AC, 340V peak).Since most people can't really tell the difference between 30Hz and a continuous light source, there shouldn't be a problem.
Zero Security Camera
Could you give us some hard numbers for ripple at different amperages and voltages? Oscillocope waveform output screenshots would be nice.
300+ Watt Linear Power Supply
ECG on your laptop!
DIY EEG (and ECG) Circuit
Arduino Programmable Constant Current Power Resistance Dummy Load
DIY Constant current load
Used the extra op-amp on the LM358 for temperature controlled fan (white, dial potentiometer sets threshold temperature). Thermistor visible on top left corner (it's not pasted on top of the mosfet yet--I need to get some epoxy or silicone or something).
So anyways, here are the pictures. Made this a week ago. Like I said, the frequency is actually *half* of what is stated. Probably a frequency calculation mistake.Anyways, not a big deal. I use the TL494/KA7500 for more serious PWM stuff. This definitely works well too, but it suffers from frequency drift based on temperature and duty cycle. Range: 0.5Hz, 5Hz, 50Hz, 500Hz, and 50000Hz, selected by header pin. Around 8%-94% duty cycle.Anyw
Let your inbox help you discover our best projects, classes, and contests. Instructables will help you learn how to make anything!
© 2016 Autodesk, Inc.