Handy count down timer with bright display

There are many uses of countdown timer. It can be used for PCB development, in a kitchen or during workout. All you need that timer was easy to set up and start. Umetronics have build simple PIC16F886 based countdown timer with four bright 7-segment displays. LED displays are driven using TLC5916 LED driver and couple dual P-channel MOSFETs. Time can be selected with rotary encoder which comes with button for select. When timer runs out there are two options for notifying – one is display flashing and another micro-switch selectable sound option along with green LED indicator. Sometimes sound might be annoying, so you can always turn it off. Timer is two AAA battery powered. So it is small portable timer for any use. Continue reading

UV PCB exposure box with countdown

If you don’t have one – build one. Probably most of self respected electronics hobbyists have one on their desk. And this is true especially if dealing with microcontrollers. Most of electronics parts come in SMD packages where simple PCB making techniques are too rough. And despite fact of miniaturization, UV exposure method gives much clearer and accurate PCB image. Here is a one version of UV exposure box built by Theodosiou Antonios. He used 4x15W black light UVA fluorescent lamps that are controlled by Atmega8 microcontroller.. User is able to set timer up to 100 minutes. Remaining time information is displayed on four seven segment indicators. And of course remember NOT to stare at lamps while they are on – UV if harmful to your eyes. Continue reading

Very simple countdown timer with 7 segment displays

This is very simple countdown timer implemented on 89C2051 microcontroller. One button is used to set time up to 99 seconds, another is for starting timer. Time is displayed on two 7 segment LED displays.   Buttons and display scanning share same pins so algorithm has to check buttons and display time on LED displays in a row sequence. Source code is included that allows yo modify program and compile. Continue reading