hi. the method I use to make PC Boards, is called the "Heat Transfer" method, using Press-n-Peel transfer paper. After applying the Press-n-Peel to a blank PC Board, I use a standard A4 laminator to transfer the toner from the Press-n-Peel to the PC Board. With the laminator set to the 125ug temperature setting, passing the PC Board trough 10 times gives me the best results.
Why the Counter?
A simple task of counting the number of passes through the laminator proved to be confusing at times. Especially when I am "multi-tasking" (boiling the kettle for hot water, prepare the acid bowl, etc).
To ensure that I no longer miss a count, I decided to build a simple counter to keep track of the number of passes :) :) :)
Design Criteria
- The counter had to be build with components I had at hand.
- Must be self-powered.
- Self-contained PC Board design. I did not want to put the project inside an enclosure.
- No loose wiring.
Component Selection
- The 7 Segment displays were salvaged from an old abandoned project. They are common cathode types.
- I decided to make use of surface mount components as much as possible. This was more for the practice of working with SMD components.
- Chip selection was the ATMEGA8 or ATMEGA328p. I decided on the ATMEGA8 as I have several of these due to an incorrect order on eBay (my mistake). Code is compatible with both.
- Buttons selected was 2 x 12mm tactile switches. Due to their larger size, they are easier to use.
NOTE :
The 7 Segment displays looks quite dim in the picture. This is due to the multiplexing of the display. The display is in fact very visible.
Step 1: Power Supply :
Because the project uses 7 Segment displays, alkaline batteries will work the best to power the project. The only PC Board mountable battery holder I had, was for a 9V battery. Thus I opted for this as the power source.
The power supply consist of an on-board battery, On/Off switch, followed by a reverse polarity protection diode. Smoothing capacitors on the input side of the regulator is not crucial, but must be rated for at least 16V.
I used a ASM1117 5V SMD regulator, but it can be replaced with a 7805 1A regulator.
Smoothing capacitors on the output of the regulator reduces high frequency noise (0.1uf), and the 100uf reduces voltage ripples caused by the 7 Segment displays switching on and off.
download ASM1117 Regulator
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