Tachtastic - a fantastic Tachometer

I know, a cheesy name - an AVR ATMega8 tachometer, with external sensors and a good design experience.

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an AVR ATMega8 tachometer, did as one of the first projects when learning AVR and doing engineering...
I missed so many classes while making this and it was so very well worth it.. :)

See project log for more details, pics and files.

The power supply and the sensor input portion schematic:

Connectors for LCD and ISP

The controller portion, ATMEGA8

The source code is provided below in the READ MORE LINK, otherwise the project page would have gone a bit too long, for ALL the files related to the project, use this link:

Read more »

  • the Sensors

    EjaadTech07/22/2014 at 07:12 0 comments

    Here are the 2 sensors I designed for this tachometer,

    1 is a reflective type, meaning it will detect movement based on the reflection of light and the other is a pass through, the counting is done when light is CUT.

  • Design Phase and PCB

    EjaadTech07/22/2014 at 07:00 0 comments

    The Tachometer needed to be small, portable, and should be extensible, so many designs were made and finally the one agreed upon was first tested on a cardboard cutout.

    On top is the ISP connector for programming, on the left are the extra pins left, the sensors input were put with a 3.5mm audio jack female connector and the 2 ICs, the Opamp and the ATMEGA8 were concealed beneath the LCD.

    I designed the PCB with big traces and some jumpers as I was just learning to make PCBs back then.. :) the final outcome:

    without the LCD

    The bottom Copper side

  • Breadboarding

    EjaadTech07/22/2014 at 06:23 0 comments

    the project started on a small breadboard on an AVR Dev board I had which used AVR ATMEGA32

    then moved to a proper breadboard with ATMEGA8 before finally going to the PCB..

    the first test with a tape on a motor and looking at the LCD for results..

    the first simplest sensor, a pass-through...

    the final breadboard, the images are old and from a very cheap camera.. :) at the right is the 7805 with a heatsink, then the 3 buttons for settings etc, then the AVR ATMEGA8 and finally the OPamp IC so I dont need to do ADC on the sensor, working as a comparator, the opamp provides a simple square wave out to the AVR, which is put on the interrupt pin, as I recall..

View all 3 project logs

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joram wrote 08/09/2014 at 23:26 point
You van make an input for sound, tot measure the speed of a combustion motor. Like for adjusting throttle of a lawnmower

  Are you sure? yes | no

ZaidPirwani wrote 08/10/2014 at 07:59 point
well, I dont know about that... but we dont have lawn movers here.. so never occured to me, also the sensor input cmoes via an op-amp as a comparator to timer input of AVR... so will that sound thing work in this scenario..?

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cBake wrote 07/24/2014 at 15:10 point
Neat! I'm working on a combination speedometer / tachometer / gear indicator project so this is an interesting read

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