Turn-key PCB assembly services in prototype quantities or low-volume to mid-volume production runs

Microcontroller driven resistor decade box

Usually resistor decade boxes are mechanical – a rotary switch comutates resistors while turning it around. But if you decide to build one, you may face problem by selecting this switch. They seems to be quite expensive and quite old fashioned. Stynus has been planing to build one of those, but mechanical switching handle didn’t look very attractive, so he decided to switch resistors electronically through microcontroller. He ended up by building three PCBs where one is a control board carrying LCD, PIC 16F648A microcontroller, rotary encoder and push button. Other two boards are resistor boards – one for high value resistors and another for low value. Each resistor board caries 16 small relays that are controlled through shift registers. Then only annoying thing with electronically controlled resistor box is that you need a power supply for it where mechanical boxes are passive. But seeing resistor value on screen probably pays off. Continue reading

The Huge LED Display Ultrasonic Range Meter

Have you ever thought of building an ultrasonic range meter before? Oh, you think it’s hard to develop this tool, then you should spend a few minutes and read this on… Frankly, ultrasonic range meter is a PIC-based project, where the heart of this stuff is PIC16F873. The ultrasonic signal, where is always received with the reception sensor is amplified by 1,000 times of voltage with the operational amplifier with two stages. It is 100 times at the first stage and 10 times at the next stage! In general, the positive and negative power supply is being used for the operational amplifier, and the circuit will work with the single power supply of +9V. Some of the parts that needed to make this ultrasonic range meter are: Sturdy case: You can make the case with the acrylic board. Variable resistor: It used to revise the error of the display by the change of temperature. Knob: You have to put it on the variable resistor. Sound horn: It is for the decrease the ultrasonic that being reflected at the thing. AC… Continue reading