I just got into planes a little and i kinda want a tach but i want to make my own for the fun of it and i was wondering if any one had plans or any know how on how to make one to pick up the prop?

Thank ya

Whoopee

To be honest with you, they are so inexpensive why spend the time and money getting parts to build one.

http://www3.towerhobbies.com/cgi-bin...&I=LXPT32&P=ML

This one is $24.99 at Tower.

But, if you are willing and able, it certainly could be done. I am sure someone with some electronics imagination could make one. It would have to be some sort of opitical pickup and a counter with a divide circuit, then some sort of display circuitry. I am an Electronics Engineer but would just buy one pre-made in a small, easy to handle package

Obviously somone can do it because they are sold.. but again, why bother!!

I found this site using Google Search:

http://www.floridaame.org/Plans/Kamr...achometer.html


This one uses four segment display for up to a count of 9999. You would want to go above that, so a five segment counter display would be necessary. In place of the Hall Effect sensor, you could use some sort of optical pickup and then count the shadow of the prop as it passes by. Divide by two for a two bladed prop, by three for a three bladed prop, and so on.

CGr.

I lighty touch the back side of the prop and count the how many times the prop taps my finger in 6 sec. I then times this number by 5. Easy.

(Because this is in the "beginners" forum, I have to say this is a joke. Do NOT touch the prop with your finger when the engine is running!) [:@]

Years ago when the Bow Tie and High Button shoes were still in style there were several kits made for tachs and panels, even TXs. Just a few years back they still had how to articles for electronics in High Flight Magazine. {IMAA} Seems those days are gone now. My basic instructors father loved to make his own gear, I think I have one of his dads kit made tachs out in my shop still. The How To Dick found the thread for shows one basic problems for the DIY people of today, cost. For the price of the parts to make that tach I was able to buy a good TNC tach. I don't tell any sport pilot to go out and buy a TNC but I do tell folks new to the hobby to buy the combo tach and volt meter from Horizon. I have done side by side testing with my tach and the H-9 combo and so far haven't found one of them that didn't give true readings. Two good meters for the price of one. And you even need the volt meter!!

You know, the way these iPhones, Droids, and so on, you can pretty much bet on there being an App that will work as a tach. The phone is just an afterthought.... "oh my, we should build a phone into this thing.. "

Now there's an idea for one of you brainiacs out there.. an RC Tach for your iPhone or Droid. What a concept!!! Only problem is, it will probably ring just when you are tach'ing your engine, then you have to decide whether to answer the phone or count your RPM's...


CGr.

Dang think I might even have the Bowtie in my closet That GB alluded to I must because I found these tachometers in my shop somewhere.

The one on the left was a actual solder it up kit or finished by Ace which is long gone now. Worked pretty darn good to but difficult to read the analog meter at the field though in real conditions.

The one on the left was a true kit but the one on the right could be considers a RTF cause ya just pulled it out of the box and held the handle on the cylinder head. The right calibrated wire would just sit there shaking its finger at you

I really agree with CG though unless you are real hard core 'solder em up' kind a guy, it usually makes more since for most just to get a modern inexpensive one.

John

Funny you mention that...

I use a "wind velocity meter" app, and a Doppler shift app on my iphone.

While both are NOT highly accurate due to utilizing the built in microphone, they are "good enough" for my meager needs.

I'll bet a variation of the doppler app could become an engine tach.

If there isn't....brb writing tach app for Droid...[8D]


lol but in all seriousness I'm surprised there's no iOS/Android tach app. There's apps for gearing calculators, apps for forward speed, apps for orientation, apps for measurement, apps for conversion, apps to tell you the weather and wind speed in your area, there's even a speedo that uses the doppler effect written specifically for RCers available for iPhone.

My Droid is 100% part of my pit box...

John, I spotted one of those in the grab box at Nice just a while back. I just went out and got my old tach my buddies dad built. THUMB TACH by HEATHKIT. There was one at Nice sitting on the counter too. Mine still works for the low end and is very steady but it no longer reads the high end?? Maybe engines just go too fast these days for it to read the prop??

That place never ceases to amaze me (Twice Nice). Denny has amassed the most eclectic collection of stuff and all for sale I have ever seen in a store type of operation. May not be the cheapest prices but if your looking for it chances hes got it buried somewhere.

I think I remember the adds for a Heath Kit tach but never saw one[8D]

Unfortunately I don't travel easily as much as I once did so don,t get the chance to visit there much. Am getting up there for the dealer show first of next month though and really looking forward to that.


John

Dealers show?? What type of show??
Gene

Yup I do remember adds for those. Thanks for sharing.

http://www.nrhsa.org/expo/

John

John, I have a vibrating wire type tac. It was called a Vibra-Tach and uses a single wire with a collar thatslides on the handle to determine RPM.

Actually it is pretty accurate but does not go to as high an RPM as the electronic ones.

jess

There's a decision there?

Heck, not from me. I am perfectly content with letting someone else do the research, work, and marketing for me.. ha.. sorry. I've done all of the design and legwork for this sort of thing in the past. I'm happy with someone else doing the work for a change....

CGr.

But if you are going to touch the prop when it is running, do it from behind!

I have an RC speedometer in my Android it works great. Get the RCSpeedo app. There is a CG calc also.

Now the new electronic ignitions have a tach plug. So you can pull your RPM just like you do from your car. The ignition. If you get an A9 transmitter, you could have the rpm sent to display there.

That ignition tach for the DLE is slick!!! But in the beginners forum I'm pretty sure most people are looking for tachs for glow engines. Because I work on so many different types and makes of engines I finally broke down and bought a TNC, nice tach but it was $100.00. Over the last couple of years when one of the guys buys the H-9 tach/volt meter I check them with my TNC. So far it is the best cheap tach I have found. Plus you get something you will use every day at the field, a volt meter. Can't beat that deal with a stick.

I broke down and bought a laser tach. I mostly use my tech at night. Cheap photocell tach's wont with lights because the power is at 60 Hz. The laser tach works at night in my shop with the lights on or off.

$60 on Amazon

I remember Heathkit. I used to pass by one of the stores when walking to school. I had just started taking electronics classes and always wanted to build one. They even had TV's you could build.

In 7th grade radio shop I made one of there radios, music type, not RC. Problem is I'm color blind. You remember those color coded little parts you soldered in?? Nothing but smoke!!! I don't think they have shops in schools any longer??

B B R O Y G B V G W

Billy Brown.... ok.. ok..

resistor color code.

CGr

And a lot of them look the sam to me!!! Even with using the VTVM to check everything I still created a lot of smoke in the shop. I did lot better in metal and wood shop.