Wireless Auto Tachometer

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Anyone performing their own automobile tune-ups knows how important it is to know your engines speed. With this tachometer, you can measure your engines speed without any connections or annoying timing lights.

Schematic

PC board layout and parts placement

Parts

Part	Total Qty.	Description	Substitutions
C1	1	0.47uF Capacitor
C2	1	47uF Electrolytic Capacitor
D1	1	8V 1W Zener Diode
D2, D3, D4	3	1N914 Diode
M1	1	200uA Meter
Q1, Q2	2	2N3391A Transistor
R1, R2, R9	3	1K 1/2 W Resistor
R3	1	47K 1/2 W Resistor
R4	1	10K 1/2 W Resistor
R5, R6	2	25K Trim Pot
R7	1	10K Trim Pot
R8	1	200 Ohm 2 W Resistor
R10	1	15K 1/2 W Resistor
R11	1	2.2K 1/2 W Resistor
S1	1	SPST Togglae Switch
S2	1	Three Position Single Pole Rotary Switch
MISC	1	Telescoping Radio Antenna, Enclosure, Power Cable and Battery Connector

Notes

Calibrate the unit as folows:

Set up this circuit:
Turn on the Tach and allow a few minutes for temperature stabilization.
Set S2 to 4 cylinders and adjust R5 for a meter indication of 180 (1800 rpm).
Set S2 to 6 cylinders and adjust R6 for a meter indication of 120 (1200 rpm).
Set S2 to 8 cylinders and adjust R7 for a meter indication of 90 (900 rpm).

To use the Tach, turn it on and let it sit for one minute to allow for temperature stabilization. Extend the antenna, select the right number of cylinders and hold the unit over the engine. If the reading is erratic or the needle jumps around, move the antenna closer to the ignition coil or spark plug wires.

The unit draws power from the car battery. If it is connected backwards, it will not work, but it won't be damaged.

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Comments

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Jay Wireless Auto Tachometer Tuesday, September 15, 2009 4:41:06 PM

interesting design I am curious if this might also work with a coil of wire wrapped around a specific plug wire or should it be the main ignition coil?

vijay harish Wireless Auto Tachometer Thursday, August 06, 2009 9:18:21 AM

sir, i am doing final yr ECE,i like automotive electonics,so i am going to do a project in dis field, i want to know all the details of the wireless auto tachometer with all the relevant details like circuit diagrams, the principle of operation and the list of components required in the diagram,project paper.I would be very thankful to you if you send me the above details to my e-mail id as soon as possible. Thank you sir.

Moye A.I. Wireless Auto Tachometer Wednesday, June 24, 2009 2:08:45 PM

Sir, i want to know all the details of the wireless auto tachometer with all the relevant details like circuit diagrams, the principle of operation and the list of components required in the diagram.I would be very thankful to you if you send me the above details to my e-mail id as soon as possible. I'm a final year student and have taken it as my project. Thank you sir.

Ernesto Forchetto Wireless Auto Tachometer Saturday, November 22, 2008 5:31:06 AM

Hi, I'm a student and therefore spend my time drinking, playing role games on my daddy's PC, and practising advanced onanism. Can you therefore send me all details of this project, properly written and bound and, of course, a ready working prototype so I can present it as my course project and get top marks. Right on man...

HARCHARN Wireless Auto Tachometer Wednesday, October 29, 2008 6:46:57 AM

hi it is usefull to all electronic related people but sir i can try on this project on my bike single cylinder. how can be possible please send me full details or sir i lived in india use 220 volt 50hz power .if it is possible please send me related details i am very thankfull to you.ok

Bob Wireless Auto Tachometer Wednesday, September 24, 2008 3:42:07 PM

can another resistor be added to have this work on a 2 cylinder Harley Davidson motor?

anonymous Wireless Auto Tachometer Wednesday, September 03, 2008 10:59:45 AM

I have been a Product Design Engineer for 28 years now, and find the Wireless portion interesting. In Reality, you still must hook up a Power source, and for any moving vehicle, It's just as easy to make the other connections as well for a hard wire connection, and without having all that Radior Frequency Static. Now for a Generator or Stationary Engine, this would be great.

anonymous Wireless Auto Tachometer Wednesday, August 06, 2008 4:54:26 AM

Sir, i want to know all the details of the wireless auto tachometer with all the relevant details like circuit diagrams, the principle of operation and the list of components required in the circuit diagram.I would be very thankful to you if you send me the above details to my e-mail id as soon as possible.

Arnel C. Wireless Auto Tachometer Sunday, July 20, 2008 10:49:27 PM

is there a way to use this with an internal combustion engine that has only one cylinder (i.e. motorcycle engines)? i'm really interested to put this in my motorcycle. please enlighten me, sir.

Wook Wireless Auto Tachometer Alternate Calibration using 50Hz Saturday, July 05, 2008 11:44:01 PM

The above calibration procedure is for 60Hz AC. Calibrating using a 50Hz 12VAC transformer If your mains power is 50Hz, set up as per the calibration schematic above, and use this procedure: Set S2 to 4 cylinders and adjust R5 for a meter indication of 150 (1500 rpm). Set S2 to 6 cylinders and adjust R6 for a meter indication of 100 (1000 rpm). Set S2 to 8 cylinders and adjust R7 for a meter indication of 75 (750 rpm).

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Jay	Wireless Auto Tachometer	Tuesday, September 15, 2009 4:41:06 PM
interesting design I am curious if this might also work with a coil of wire wrapped around a specific plug wire or should it be the main ignition coil?
vijay harish	Wireless Auto Tachometer	Thursday, August 06, 2009 9:18:21 AM
sir, i am doing final yr ECE,i like automotive electonics,so i am going to do a project in dis field, i want to know all the details of the wireless auto tachometer with all the relevant details like circuit diagrams, the principle of operation and the list of components required in the diagram,project paper.I would be very thankful to you if you send me the above details to my e-mail id as soon as possible. Thank you sir.
Moye A.I.	Wireless Auto Tachometer	Wednesday, June 24, 2009 2:08:45 PM
Sir, i want to know all the details of the wireless auto tachometer with all the relevant details like circuit diagrams, the principle of operation and the list of components required in the diagram.I would be very thankful to you if you send me the above details to my e-mail id as soon as possible. I'm a final year student and have taken it as my project. Thank you sir.
Ernesto Forchetto	Wireless Auto Tachometer	Saturday, November 22, 2008 5:31:06 AM
Hi, I'm a student and therefore spend my time drinking, playing role games on my daddy's PC, and practising advanced onanism. Can you therefore send me all details of this project, properly written and bound and, of course, a ready working prototype so I can present it as my course project and get top marks. Right on man...
HARCHARN	Wireless Auto Tachometer	Wednesday, October 29, 2008 6:46:57 AM
hi it is usefull to all electronic related people but sir i can try on this project on my bike single cylinder. how can be possible please send me full details or sir i lived in india use 220 volt 50hz power .if it is possible please send me related details i am very thankfull to you.ok
Bob	Wireless Auto Tachometer	Wednesday, September 24, 2008 3:42:07 PM
can another resistor be added to have this work on a 2 cylinder Harley Davidson motor?
anonymous	Wireless Auto Tachometer	Wednesday, September 03, 2008 10:59:45 AM
I have been a Product Design Engineer for 28 years now, and find the Wireless portion interesting. In Reality, you still must hook up a Power source, and for any moving vehicle, It's just as easy to make the other connections as well for a hard wire connection, and without having all that Radior Frequency Static. Now for a Generator or Stationary Engine, this would be great.
anonymous	Wireless Auto Tachometer	Wednesday, August 06, 2008 4:54:26 AM
Sir, i want to know all the details of the wireless auto tachometer with all the relevant details like circuit diagrams, the principle of operation and the list of components required in the circuit diagram.I would be very thankful to you if you send me the above details to my e-mail id as soon as possible.
Arnel C.	Wireless Auto Tachometer	Sunday, July 20, 2008 10:49:27 PM
is there a way to use this with an internal combustion engine that has only one cylinder (i.e. motorcycle engines)? i'm really interested to put this in my motorcycle. please enlighten me, sir.
Wook	Wireless Auto Tachometer Alternate Calibration using 50Hz	Saturday, July 05, 2008 11:44:01 PM
The above calibration procedure is for 60Hz AC. Calibrating using a 50Hz 12VAC transformer If your mains power is 50Hz, set up as per the calibration schematic above, and use this procedure: Set S2 to 4 cylinders and adjust R5 for a meter indication of 150 (1500 rpm). Set S2 to 6 cylinders and adjust R6 for a meter indication of 100 (1000 rpm). Set S2 to 8 cylinders and adjust R7 for a meter indication of 75 (750 rpm).