(INSOMNIACS) balls deep.

[RatVonDude]

[dr.feltersnatch]

[q-tip]

^^^^wwooooo!!""

[Spoona_Jay21]

Blah, Battery on my Saws-all died... so i have to finish my new headlights tomorrow =/

[Royal Sierra]

My ex used to sell her foodstamps for heroin.

 

Oregon city lyf

[RatVonDude]

This is the one too read

[Royal Sierra]

I got one of those $10 wifi OBD2 scanners off of ebay. Its the shit. I get all the info on my phone/laptop. I'm gonna plug it into the cars at work

 

[jastrunk97]

Anybody know what this is? HINT, its from a sewing machine 

[tr8er]

I need a digital Tach. No roundy roundy. Just numbers, or even better a straight line that just progressively gets longer the higher the rev. For this I hunt. And it's gotta be smallish. Internets to the finder of a product that is still findable.

[tr8er]

Anybody know what this is? HINT, its from a sewing machine

 

Nope, but that looks exactly like the wood finish of a 40's era singer sewing machine table. I refinished one last Christmas.

[jastrunk97]

Haha thats my desk and I got it from Costco

[Royal Sierra]

I need a digital Tach. No roundy roundy. Just numbers, or even better a straight line that just progressively gets longer the higher the rev. For this I hunt. And it's gotta be smallish. Internets to the finder of a product that is still findable.

Dude ebay has digital 2" tachs for 10-20 bucks. Even with free shipping

[Royal Sierra]

I'll take those internets sir

 

[RatVonDude]

Douche Lord Reanimated

[TENDRIL]

[TENDRIL]

 

 

take me back!

[hang_510]

[hang_510]

[RatVonDude]

[tr8er]

I'll take those internets sir

 

I'll accept fault. I should have mention my need for a Tach that would work with a four cylinder engine. Not really running 100khz.

[Royal Sierra]

Look, theyre on there for less than $20..

[Royal Sierra]

And what does 100khz have to do with it being a 4cyl? serious question

[tr8er]

I'm no expert on this topic, though in my search, I've ruled out similar items as not easily adaptable for my cause. Basically, automobile tachs are preset to work on the engine that they are meant for. They read pulses from your coil and apply a math formula to derive at an RPM. Not that it is complex, but it is math. So if you had a tach from a 6 cyl, you couldn't use it for a four, eight, ten cyl. Etc. I think it would be the cylinder count divided by two, cause the shaft rotates twice per spark (four stroke). In my case two. Every time the tach sees two pulses, the engine has completed one revolution. Now it just needs to measure how fast it sees two pulses. This is Hz (occurrence per second). A car tach takes frequency (Hz) multiplies by 60 (seconds), then by the cylinder count, divided by two, to give you RPM. So at idle (750 RPM). The tach you are looking at would read 25HZ. Or at 6000RPM it would read 200Hz.

 

I'm not looking to do the math, or get used to odd numbers while driving. But it would be unique. I want good ol RPM numbers.

 

That's my understanding of what car tachs take into account. I hope someone with more knowledge will correct me if wrong.

 

I believe the tach you are pitching would be to measure an electric motor, or something similar with a 1 to 1 ratio, and where frequency and RPM were analogous.

[smoke]

While this is most likely not the place for 'fancy talk', it's like this...with a regular tach on an engine like ours, it's just an analog circuit with a couple of transistors. The first transistor in like detects a wave from the points being opened. The pulse from the points is just an oscillation that only lasts a millisecond or two. It starts out an a low AC current of about 50 volts that is a split second is dropped down to about 24 volts DC. When the spark is done, it then drops to 12 volts until the points close up again.

 

So in your tach, the first transistors job is to convert that to a square wave pulse that has about 2 milliseconds of elapsed time. The output of this is pulses that last a couple of milliseconds when on, the rest of the time it's off, just one set of pulses each time the points open. The next transistor in line acts as an amplifier to actually drive the tach off of those pulses. The more amps of current it gets, the more juice it gives the needle to move. 

 

The difference in tachs set to 4 6 or 8 cylinder is the number of pulses and how the tach deal with that. So like 4 to 8 it will recive two pluses but needs to convert it to one, otherwise it will read exactly double the rpm. As far as lights go, if you were really motivated, a guy could probably build something like this from radio shack. It would be a lot of soldering diodes and leds, but could be done. However, I am just sure you could probably buy something like that, ready to go on the cheap.

[TENDRIL]