Want a small, non-rice tach for my Camry:

[kenratboy]

OK, I saw this:



And thats not what I am looking for...

I am 6'6 and the steering wheel blocks the tach from 3,500 RPM's to almost redline. This is a PITA, as I have to sink my head down to see whats going on. I want to be able to use my perepheral vision to see whats happening in the RPM department.

Can anyone recommend a non-rice (as in, maybe 3-4" diameter), semi-serious (as in, I want to USE it), tach? If so, what brands and models should I consider? I am familiar with AutoMeter. Also, how do you install them (easy or hard)?

Thanks!

[Fresco Bob]

i share your pain. do u have power seats? cause in my 'rents cam if i put the seat as far down as it will go, and lean it back a bit more, then i can see everthing clearly. i can even see the top light at intersections, and dont have to look at the lower one to the side of the intersection.

[kenratboy]

Originally posted by Fresco Bob
i share your pain. do u have power seats? cause in my 'rents cam if i put the seat as far down as it will go, and lean it back a bit more, then i can see everthing clearly. i can even see the top light at intersections, and dont have to look at the lower one to the side of the intersection.

lol - same with me at lights, sometimes I need to hunker down. I don't have power seats, but am perfectly comforatable, except for the tach. I don't have (or want) a sunroof, so that helps a lot.

[alex]

ahhhhhh.......i'm so glad i'm short

less weight.......hehehe

make my bike go alot faster.........135 lbs of me on a bike = not extra weight = wheelie easier

[kenratboy]

Originally posted by alex
ahhhhhh.......i'm so glad i'm short

less weight.......hehehe

make my bike go alot faster.........135 lbs of me on a bike = not extra weight = wheelie easier

Hey, I'm like 2 of you

I wish I was 6' even, that would let me fit in abot every car available.

[Tony the Tiger]

Here are some mini tach that I found with a quick browse on autometer's website:


2-3/4" in diameter... slightly bigger than regular A/F gauges:

Here's the link to their page:
http://www.autometer.com/hp/2003_cat...utogage/7.html



2-1/16th" in diameter... the same size as the regular gauges.

Here's the link to the page:
http://www.autometer.com/hp/2003_cat...rmance/40.html

[kenratboy]

This little guy actually caught my eye:



Link:

3.75", built-in shift-light (not the rice 2" external LED), 8,000 RPM range (not overkill, like a 10 or 12k RPM gauge) and an adjustable range for redline. Looks nice.

[jornie14]

My cam doesn't have a tach so I made my own out of LED's. One LED lights up every 500 RPM, all green except for 6000 and 6500, those are yellow and red.

It can go anywhere because it is flat. It's pretty small (about 4" x 1.5" x .5").

The best part is it only costs about 10$ and some solder to make.

[arcasmachineracing]

Originally posted by alex
ahhhhhh.......i'm so glad i'm short

less weight.......hehehe

make my bike go alot faster.........135 lbs of me on a bike = not extra weight = wheelie easier

I am right with you bud! Heh!

[jm_2thow]

My cam doesn't have a tach so I made my own out of LED's. One LED lights up every 500 RPM, all green except for 6000 and 6500, those are yellow and red.

howd u do that?

[Tercel GTS]

serious, make a how to

[jornie14]

here is a quick how to. If you guys want I will post a better one with the schematic I use later this week.

Basic How To:

it runs off a frequency to voltage converter. Tach signal and battery power go in and voltage based on RPM comes out. The f/v converter I use is made by National Semiconductor and is part number LM2917N. This link should get you to the data sheet:

http://www.national.com/ds/LM/LM2907.pdf

On that data sheet it tells you how to make it work with a tach signal. I used the "voltage driven meter based on engine RPM" setup.

Then take the Vout and connect it to a series of comparitor op-amps (LM741) to drive the LED's. The circuit I use is attached, you need one for each LED.

Vref is the voltage you expect the f/v converter to put out at a given RPM. The op-amp compares it with Vout the actual voltage being put out at the current RPM. If Vout is greater than Vref then the op-amp puts out B+ (12volts), Which lights the LED.

Vref is determined by a voltage divider. The value of those two resistors takes B+ and reduces it for Vref by this equation:

Vref=(B+)*(R1/(R1+R2))

I put it all together on a premade pc board I bought at radio shack for $2.25.

If you have questions or you guys really want me to do a in depth how to reply and let me know. I hope this made sense, I have never done a how to before.

I'm also still testing my circuit to make sure it doesn't draw too much battery power.
-jornie

[88 LE]

A full schematic would be cool.

I did a cross reference with NTE on the 2 IC's you listed and came up with some data sheets.


LM2917N:

http://www.nteinc.com/specs/900to999/NTE995.html


LM741:

http://www.nteinc.com/specs/900to999/NTE941.html

[jornie14]

small corrections.

The equation for the voltage divider is:

Vref=(B+)*(R2/(R1+R2))

I adjusted the design given on the national semiconductor web site. I took out the diode going between lead 11 and 12 and grounded lead 11 (got rid of the 10k resistor between B+ and lead 11).

-jornie

[jornie14]

oops the op amp is powered backwards too. should look like this:

Sorry about all the messups... too little sleep.