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

Add A Comment

giovani Wireless Auto Tachometer Thursday, September 25, 2014 10:41:07 AM

sir i want to know if this can be integrated in a mechanical electric meter. and how reliable it is in measuring the rotation of a disk in that particular meter. thanks..please do reply.

anonymous Wireless Auto Tachometer Saturday, June 16, 2012 10:06:46 AM

I like the circuit. I have been drinking every day for weeks and consequently, I am out of money. Please send me a built circuit and some money so that i may drink and continue with school. Thanks and please hurry. I have a final coming up and there is a wicked good band at the pub down the street and I need beer money and also have no time to work or build this circuit. i will submit this circuit as my own design. Hope you don't mind. Thanks again.

rohan Wireless Auto Tachometer Saturday, April 30, 2011 9:44:58 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.
(Editor's notes: Did you even read the page?)

Amazed Wireless Auto Tachometer Tuesday, November 23, 2010 8:12:31 AM

I am truly amazed at how many of the people placing a comment is willing and able to rip off an idea for which they can claim no credit and pass it off as their own. If you are "studying" electronics study the circuit and draw you own conclusions you lame leeches. Out

sillybunny Wireless Auto Tachometer Wednesday, July 28, 2010 3:22:28 AM

hello 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,project paper and also coding for the programming..I would be very thankful to you if you send me the above details to my e-mail id as soon as possible so that i can use it as my reference for my final year project.. . Thank you sir.

Bob Wireless Auto Tachometer Sunday, June 06, 2010 5:49:31 PM

I like the idea of this circuit, however the circuit itself is not designed very well, you basically have to keep calibrating it constantly because it's very sensitive to temperature changes.

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...

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giovani	Wireless Auto Tachometer	Thursday, September 25, 2014 10:41:07 AM
sir i want to know if this can be integrated in a mechanical electric meter. and how reliable it is in measuring the rotation of a disk in that particular meter. thanks..please do reply.
anonymous	Wireless Auto Tachometer	Saturday, June 16, 2012 10:06:46 AM
I like the circuit. I have been drinking every day for weeks and consequently, I am out of money. Please send me a built circuit and some money so that i may drink and continue with school. Thanks and please hurry. I have a final coming up and there is a wicked good band at the pub down the street and I need beer money and also have no time to work or build this circuit. i will submit this circuit as my own design. Hope you don't mind. Thanks again.
rohan	Wireless Auto Tachometer	Saturday, April 30, 2011 9:44:58 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. (Editor's notes: Did you even read the page?)
Amazed	Wireless Auto Tachometer	Tuesday, November 23, 2010 8:12:31 AM
I am truly amazed at how many of the people placing a comment is willing and able to rip off an idea for which they can claim no credit and pass it off as their own. If you are "studying" electronics study the circuit and draw you own conclusions you lame leeches. Out
sillybunny	Wireless Auto Tachometer	Wednesday, July 28, 2010 3:22:28 AM
hello 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,project paper and also coding for the programming..I would be very thankful to you if you send me the above details to my e-mail id as soon as possible so that i can use it as my reference for my final year project.. . Thank you sir.
Bob	Wireless Auto Tachometer	Sunday, June 06, 2010 5:49:31 PM
I like the idea of this circuit, however the circuit itself is not designed very well, you basically have to keep calibrating it constantly because it's very sensitive to temperature changes.
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...