Pro Tips: Use a Hot Air Gun to Reflow Solder


A good hot air solder rework station costs well upwards of $100. If you have just a few parts you need to reflow, you can use a common heat gun available at most hardware stores for around $30. These guns have all kinds of uses and are commonly used in construction to strip paint. They are usually around 1000W and some have temperature control. I use a Wagner HT1000, which has selectable 750F and 1000F modes.


Common solder melts around 500 degrees F, no problem for most of these guns. These guns push a lot of air and can blow away smaller components if they aren’t held down, so be careful! For hobbyists building boards with lots of small surface mount components, Continue reading “Pro Tips: Use a Hot Air Gun to Reflow Solder”

Drive an RC Servo from Analog Voltage


This is a circuit I designed to generate a PWM signal for an RC servo given an analog voltage or high frequency PWM.  It has no microcontroller and can be built with one quad op-amp and passive components.

The op-amp I used in my implementation is a NJU7034D-ND, available from digikey, but any rail-to-rail quad op-amp will do.

Since the input stage has a low pass filter built in this circuit will accept a high frequency (>~5kHz) PWM as an input in addition to analog voltages.

Continue reading “Drive an RC Servo from Analog Voltage”