Simple Servo Tester - 555 timer based

A simple 555 timer based servo tester, allowing manual movement or control of common pulse-width controlled radio-control / robotics style servos. This is a quick build on a prototyping board, using a NE555, 680 Ohm and 47K resistors, a 5K (or 4K7) potentiometer, 470nF capacitor and a 1N4148 diode. For a high power servos or a "weak" power supply a decoupling capacitor is also needed across the power supply. The very high torque servo I first tried it with turned out to need more than the initial 5V USB supply could provide - it worked using 6V from a bench supply, plus a larger, 1000uF, decoupling capacitor. A .pdf copy of my original 1978 article about this design is available on my website, here - the "RC Failsafe" https://robert-jenkins.co.uk/site/ind... It can of course also be built on a small piece of stripboard as a permanent item of test equipment, instead of on a protoboard. Video content: 00:01:00 - Parts used 00:01:18 - Schematic 00:01:52 - Assembly 00:09:32 - Power on (with a servo that needed over 5V) 00:09:50 - Checking supply and output 00:11:55 - A normal power servo, and it works! 00:13:54 - A micro servo, also working fine 00:15:35 - Experimenting with the 35Kg type again 00:20:35 - Back to the normal servo 00:21:43 - Different power source, and high power servos working 00:22:35 - showing the need for a decoupling cap to aid stability I was thinking of another article when I mentioned early 80s in the video; also saying three resistors, which should have been stated as including the pot not in addition to the pot. That's what I get from not preparing any kind of notes or script!