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

Eye catching LED ring display

There is always a dilemma on how to build an indicator for your next project. There are many options like LCDs, LEDs, VFD. Sometimes one or another is enough, but eventually you want something eye catching and obvious that could be seen from distance. For instance for water meter a dial based display probably is better than LCD. IT can be seen from distance and is informative to tell how mutch water is in tank. John simply built a LED ring display out of 16 single color LEDs. He needed to use shift register, but he thought that popular 74xx595 chip is very current limited. Total current draw shouldn’t exceed 50mA which is like 2 more powerful LEDs at a time. So he looked for more proper shift register and came op with better one – TLC59282 16-bit shift register which is capable of sinking 30mA on each pin. Neat feature of this chip is that it comes with current setting pin, meaning that you only need single resistor for setting current for all LEDs. This saves space on the… Continue reading

Digital clock with voltmeter based display

There are several digital clocks with analog displays around. They are somewhat unique giving the feel of the retro. With proper enclosure such clock becomes great design element. Following project was inspired by Alan Parekh multimeter clock. Originally there were three analog multimeters used in voltage mode to display hours, minutes and seconds. In this project there are three analog voltmeters used with their faces printed to match time scale – one for hours, one for minutes and third for seconds. The clock code runs on PIC16F628A but time is synchronized every 30 seconds to master clock. Analog displays are driven through transistors by generating PWM signals that are equivalent to DC voltage. This part is fairly easy to implement on microcontroller. The clock also has a Chime circuit based on ISD1730 that gives “tick tock” seconds sound. Continue reading

Very basic car battery charger on PIC12F683

Charging lead acid car is fairly simple. You need to take care of charging current which should be around 0.1C and charge up to 13.4V battery voltage. Having this in mind, it is easy to build charger out of few parts available. Pityukecske have shared his version of battery charger on instructable. He has chosen a PIC12F683 microcontroller which controls relay switching charging current to battery and also monitors battery voltage on one of its ADC inputs. Current circuit doesn’t have much flexibility – charging current is basically driven directly from transformer and diode rectifier. It is visible on panel ammeter. So transformer is chosen to meet current requirements. Microcontroller monitors battery voltage. Since it is over 12V there is a resistor voltage divider used to scale voltage to microcontroller working limits. Once voltage reaches 13.4V, microcontroller shuts current by deactivating relay. Couple status LEDs indicate charging state. Simple solution that works in most cases. Continue reading

Testing stepper motors with pulse generator

This is a quick portable circuit used to test stepper motors. It is based on small PIC 12f675 microcontroller. The pulse speed is changed with potentiometer. It allows smoothly variate between 20Hz and 3kHz. It has couple jumper bridges to select enable and dir pins. Servo tester is powered with four NiMh rechargeable batteries that give total 4.8V.  This circuit can also be used as general purpose pulse generator if needed. Continue reading

Nice looking PIC24 watch with OLED

Jared has been working on his OLED watch and it seems that it reached the stage when if can be to test. Watch is equipped with several great features like USB HID communication, time, date with events and accelerometer. Watch firmware is RTOS based where he wrote all necessary drivers, graphics engine and PC applications for setting things up. He designed schematics and PCB by himself using Altium Designer software having small size in mind. Jared was about to look for 3D printer to do the case, but he found that aluminum case from iPod Nano fits just right. Watch already works, but there is much work to do on user interface and probably new features like Bluetooth, magnetometer and other things that bring it to fully featured smart watch. Continue reading

PIC based Weather radio

This one is still a pending project, but you might give it a try as it’s a interesting one. In this project a weather radio is tuned using PIC and as soon as there is a weather alert, it’s broadcasted on the LCD as well as the speaker of the weather radio. As of now, PIC powers up, resets and powers up the radio, then tunes the radio via I2C to 162.55MHz. It finishes up by reading back the status and then dumps the Tuned Frequency and RSSI (Received Signal Strength Indicator) on to the LCD. The output from the audio amplifier is a little weak and hence might require a second stage amplifier. The author also wants to add buttons for “quick tune” to the common frequencies (.40, 425, .45, etc.) and one additional monitor/standby switch. The PIC is able to tune the weather station which was brought from spark fun using I2C protocol. The hardware schematics have been provided on the website and also what work has been done till now. Continue reading