Signal conditioner circuit. It takes voltage from one input and add it with voltage from other input. Both input can vary from -10V to +10V giving dynamic range at output from -20V to +20V. Used for conditioning sensor signal from -5V to 5V so it can be fed to a closed loop system that need 0-10V input. Opamps: OP07 Microcontroller: ATMega8 (for voltage display purpose) Analog Power supply: +-24V, taken from PoE adapter Digital Power supply: 5V from usb charger.
So I had to made voltage regulator input 70V output 5V 100mA. I only have MP1584 switching voltage regulator that have 28V maximum input voltage. So I need to think one of (inefficient) way but simple and the components are widely available. My solution is using a lot of (60) 4148 diodes. I choose using smd components because it speeds up building process a lot. Just put a good amount of solder paste, put the diodes in the corresponding manner, and stuff it inside toaster oven for 4 minutes. Next I tested the diodes solder each one by one to ensure good connection and no bridges. And then feed it with 70V power supply and it works like a charm. PS: successfully made this 25 units in 1 week #smd #oven #reflow #solder #LL4148 #mp1584 #voltreg #voltageregulator
Another repair: the pcb are toasted. After through analysis, the burnt part is digital communication line, they were shorted with high voltage mains line. The effect is catastrophic it broke mostly 3 parts: microcontroller, line transceiver, 5V supply regulator. The module itself is already good design and has many safety countermeasures. Then after checking on the field. The problem lies on the mains and data line are put on the same conduit and junction box. Some junction boxes are not waterproof and failed to provide protection from rain. This is RGB DMX controller from led display at previous post. Fix: I had to piggyback some components, put new microcontroller chip, the firmware is unobtainium so I tried to reverse engineer the protocol and did succeed 90%. Can change color, can change device address manually but not automatically, using the same original DMX software from respective brand (Ph***ps)
Radial Hexapod with 3-DOF each leg. Capable of going on uneven terrain showed by walking through small stairs. Please forgive the video quality. This video is 7 years old. Original link: https://youtu.be/A_OmrZ_XwGk
A bunch of toasted attiny2313 chips. So here is the story: there are connector that should be connected to a switch and other connector to mains voltage. The label are pretty solid on the case. But somehow these electrician connect them wrong way around. The connector for switches are directly going to digital input of microcontroller. So the microcontroller are fed directly with mains voltage. Moral of the story: human error always exist. never connect anything outside to microcontroller directly, must use optocoupler or any other means. Use different size polarized connector for each different usage. #AVR #attiny2313 #toasted #fried