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Old Sep 05, 2010, 06:51 PM
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Near Andover, Southern England
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Help!
best engine tach - what to buy? advice please

hi guys, i'm hoping for some advice on which tach to buy.
i've got an old abused digital/otical tach already so i know how they work, but i'm not sure its reading right. i've done the old 'point it at a domestic light bulb' trick and it reads ok for that (303). using with my engines though gives some strange variable readings that go up and down a fair bit - so i'm gonna invest in a new one (i don't mind if its a bit pricey, as long as its good i.e. consistant,reliable and accurate).

so, what do you recommend?
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Old Sep 05, 2010, 08:52 PM
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oskartek's Avatar
Cedar City, Ut.
Joined Dec 2009
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I have owned several digital tachometers and have never been entirely satisfied with their performance.
I wish I could find an old Heathkit Thumb Tach.(they were analog.)

I get the best results if the prop is directly between the light source and the tach.

You may find this website helpful, they offer several tachs of different design including LASER tachometers although they may be somewhat expensive.

http://www.calright.com/ca_122.aspx?...FUfu7QodCFn51Q

Good luck, Oscar

A man that hates kids and dogs can't be all bad. But then, I've met some dogs that I liked.
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Old Sep 06, 2010, 07:50 PM
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wow! thanks Oscar. Probably a bit more than i was hoping to pay, but they look like real good kit. better start saving lol
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Old Sep 06, 2010, 08:54 PM
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AB Bob's Avatar
USA, VA, Spotsylvania
Joined Jan 2009
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A quick google for photo tachs came up with this:
http://www.amazon.com/Digital-Laser-.../dp/B000EUT9ZS Only about $30 w/ good accuracy numbers.
I personally use the Hobbico mini digital tach, about $22 from Tower Hobbies.
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Old Sep 08, 2010, 06:13 PM
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USA, MA, Weymouth
Joined Mar 2004
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Over in the USA, the TNC tach has long been considered the best one around...

Dear Rick Rotorhead:

The PIPE Here...even though I'm GOING to have to go "on the dole" very, very soon (been out of work for just about 2 years now, and my unemployment checks stop this week) when I CAN get back to work, it's the model engine tach you can find at...

http://www.fromeco.org/products/05frctnc/default.aspx

...that's the latest version of Tony Criscimagna's "TNC" digital readout model engine tach, long considered to be the best available in North America, that I'd be getting for upgrading my 1980s-vintage field support gear.

The "Don's Hobby" store over here also has it available for a small bit less, I believe, at http://www.donshobbyshop.com/access.htm - scroll about 25% of the way down that page, and you'll see it on the right of the browser window.

I've got one of the older 1980s vintage Futaba "TachoTimer" units that only reads out to "hundreds" of RPM...mine still works, but with a TNC tach you'll get at least a much better 5 RPM resolution instead.

I've attached photos of the "old" version (discontinued for quite some time now) beside the version that Fromeco makes and sells, and that Don's Hobby sells for a little bit less than Fromeco does...perhaps a bit later I might even add a photo of my grizzled old Futaba TachoTimer to this reply, for a comparison with what's available these days.

Hope this helps you out with picking a REALLY good digital tachometer for your RC flyin' needs...

Yours Sincerely,

The PIPE....!!
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Old Jul 27, 2012, 03:16 PM
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My TNC is backoreded from FromeCo, I called and they are waiting on screens (LCD), but told me to call Don's Hobbies, and see if they had any in stock. I called, ordered, and called fromeco and cancelled the back order. Looks like a pretty good tach...!! A bit pricey but WTH, it's only money....!!
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Old Jul 27, 2012, 04:01 PM
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The TNC is still probably the best on the market at $100.00 but I have taken mine and compared to with every one of the combo tach/volt meter that was sold through H-9. I think they are an ACE product. So far I haven't found any of the H-9 units that didn't read exctly as my TNC. Most sport pilots don't really need a tack very often but everyone needs a volt meter. I rebuilt and tuned so many different engines I needed the TNC and I'm glad I have it. That was just a bunch of money for a tach.
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Old Jul 28, 2012, 08:06 PM
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I have to say the Fromeco TNC tachometer is the best so far. Albeit maybe one of the old time German or Swiss made mechanical tachs might still be more accurate. But I love the Fromeco tach as it works in the shade or sunlight and you don't have to get close to the prop for it to work either. Now if you do not need a tach to work in the shade or when it is getting dark or something, but you can live with the tach only working in broad daylight (a overcast sky usually causes them to quit working too), then the cheaper tachs work fine.

I still have my Heathkit Thumbtach and it still works too. But it is a daylight only tach though.
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Old Jul 29, 2012, 10:08 PM
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A question to other TNC users, not someone that has seen them or know someone with one but USERS! Do your tach RPMs move up and down a lot or does your tach pretty much stick at an RPM and stay there?? Mine moves a couple hundred up and down but I have seen the older black case tachs pretty much stick at one RPM. Just wondering.
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Old Jul 30, 2012, 05:12 PM
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Yes the RPMs of a engine do vary. The more rich the engine is running at the more the rpms will vary. The more lean you run the engine the less the RPMs will vary. Digital tachs tend to show this more than the old analog tachs do. Also the more precise the tach is the more variation in RPMs it can show too. But don't run the engine too lean of course. Also the rate at which they update the display can also cause more variation too. A slow number of updates would tend to make it look like it isn't varying a lot in RPMs. A faster update rate would show more variation. Anyway, I think they changed the programming inside the tach thus leading to the change you noticed.
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Old Jul 31, 2012, 11:51 AM
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Quote:
Originally Posted by earlwb View Post
Yes the RPMs of a engine do vary. The more rich the engine is running at the more the rpms will vary. The more lean you run the engine the less the RPMs will vary. Digital tachs tend to show this more than the old analog tachs do. Also the more precise the tach is the more variation in RPMs it can show too. But don't run the engine too lean of course. Also the rate at which they update the display can also cause more variation too. A slow number of updates would tend to make it look like it isn't varying a lot in RPMs. A faster update rate would show more variation. Anyway, I think they changed the programming inside the tach thus leading to the change you noticed.
I asked because I had used one of the older black TNCs and it didn't bounce around like my Blue TNC, just wondering if my TNC is morfe sensetive then the older ones? I was taught to tune an engine by Clarence Lee before I was a teen but thanks for the advise.
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Old Jul 31, 2012, 12:43 PM
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You are a lucky guy to get to know Clarence Lee personally. He is great.
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Old Jul 31, 2012, 07:09 PM
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Originally Posted by earlwb View Post
You are a lucky guy to get to know Clarence Lee personally. He is great.
Very early 60s when he was still working on his K&Bs. We kids would circle around him and he would do a sort of clinic thing for us. Did a show and tell on things like port timing and compression so we understood how different engines would have lower rpms and different torques, At the time he was working on different things for control line engines. Those were the days when boys learned from the older guys and books, RC at the Dam Basin was just getting going but I was into free flight and control line. I never really got to know him but even in the last decade I had him doing some work on a couple of my YS engines that I over tightened a couple of screws then messed up with a tap. I just bought a NEW/USED YS 1.10 that someone else messed up and Mr. Lee repaired. In the box was a note from him telling the owner what not to ever do again. A big score for me, the engine was so new it was blowing out gray mater the first five or six flights until it broke in. The man still does good work and this engine runs perfectly. If therre were any kids flying thesde days I would do the same thing but computers and games win out!
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Old Jul 31, 2012, 09:45 PM
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Lacona, NY
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I guess I'm the only one that uses a Magnum Digital Mini Tach. (I must be special)

It works good enough for me, but also I do have a good ear and can adjust a engine by feel and sound. Once a guy thought I was full of it and decided to test me at my club. I was only a few clicks off on a simple 2-stroke.

On the 4-strokes I struggle with it a little more, so I wip out the tach to help me get it close enough. I like to stay a little on the rich side with my 4-stroke engines.


Pete
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Old Jul 31, 2012, 10:04 PM
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I can adjust two strokes by ear just fine, but the four strokes don't sound like the 2 strokes, so I generally use a tach on them, as the difference in RPMs when you back off the needle from peak is harder to notice by ear. I think if I ran my four stroke engines more, I could develop a better ear for them, but I haven't done that yet. I still tend to bounce back and forth between the engine types when I go flying, etc.


That is a good story Gray Beard, thanks for sharing.
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