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UV-Timer

simple Timer-Addon for my UV-exposure unit

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This Timer-Addon controls the pcb exposure time of my cheap C.I.F. UV-Exposure unit.
It came without a timer, so i designed one, that i do not have to stand aside with a stopwatch.
It is a simple and cheap setup, which can be used in various applications.

The setup consists of a Logic Board and a separate 230VAC Power Board.

Logic Board

This board uses a rotary encoder and the 7-segment display + LED as userinterface. The ATtiny84 handles the timing, userinterface and switches the relais on the power board with a transistor.

Power Board

This board is mounted isolatated inside the case. It supplys a regulated 5VDC voltage for the logic board out of a 230VAC mains voltage using a LM2940 low-dropout regulator circuit. A 5V relais switches the current for the uv-lamps. A microfuse protects the ciruit.

Little milled coutouts in the pcb should prevent potiential surface leakage between the small contactspacing of the little relais.

Functions

The time period can be set between 1 second an 60 minutes. Seconds can be set by rotating the encoder, minutes can be set by press-rotating the encoder.

The count-down timer can be started and stopped by a short press on the encoder. The relais and LED will be controlled accordingly.

A longer press on the encoder starts the count-up timer without switching off the lamps.

A long press stores the time period to the EEPROM for the next exposure and will be loaded on start of the device.

Userinputs are confirmed with little display animation and a tonesequence.

  • 1 × ATtiny84 Microprocessor
  • 2 × 74LS595 ShiftRegister
  • 1 × 7-segment Display 3digit
  • 1 × Rotary Encoder up, down, click
  • 1 × LED, Transistor, Relais showing state and switching uv-lamps

View all 6 components

  • ​Material costs

    java-jim06/07/2015 at 13:04 0 comments

    Logic Board - 4,53 EURO

    Power Board - 3,82 EURO

    Total - 8,35 EURO

  • Optimising the Timer accuracy

    java-jim06/03/2015 at 10:27 0 comments

    I measured a 15 seconds deviation in a 10 minutes exposure run resuling from the uncalibrated internal 8MHz Oscillator. So an enhancement could be the tuning of the internal osccillator on AVRtiny84 chip with the OSCCAL register...

View all 2 project logs

  • 1
    Step 1

    Software

    The Arduino sourcecode is available on Github. Arduino-Tiny Core support files needs to be setup for ATtiny84 and the enhanced pin change interrupts for tiny processors library is needed. I used AVRdudess and a ISP-PogoPin connector for downloading the firmware.

    Hardware

    The EAGLE schematics and board files as well as the CNC drill/mill and LaserCutter (for SMD stencil) files are available on Github.

View all instructions

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moltocair wrote 06/07/2017 at 00:27 point
I am from indonesia and interested in project can you help to send design layout pcb uvtimerthis to me, i want to make it for his attention i thank you very much

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