what tach are you using?
 

I have an older Glo Bee tach and it leaves a lot to be desired. It seems to jump around a lot and the readings vary depending on the angle the tach is held relative to the prop disc. I have heard that the TNC tach is really accurate but expensive. Is there a tach that will hold an accurate reading or is TNC the only way to go? Does anyone know where to get a TNC tach?

what tach are you using?
 

I used to have a Glo Bee tach, but I ditched it after a couple of weeks. I'm using the Hobbico tach now, which works better than the Glo Bee. The TNC tach is currently on my shopping list.

Hangar 9 DVT...
 

... costs around $45 but it's a combo unit. It tachs 2, 3 & 4 blade props as well as being a digital voltmeter for Tx and Rx.

The problem I'm having with it is that I like to use it at home in the evenings when running up engines. This is not the best time to try and use an optical tach. If it's too late or cloudy then the reading become erratic or you get no reading at all.

With cloudy conditions and a grey plastic (APC) prop its no wonder the tach can't see it.. :p

These tachs ( all of 'em, not just H9 or Glo Bee) require good strong light and the light source needs to be the opposite side of the prop from the tach. You also might need to find a way of providing good contrast by painting the prop for example.

what tach are you using?
 

tiggerinva, try a TNC one time and you will be surprised as to just how little light it needs to get a stable reading.
Ed M.

what tach are you using?
 

bentgear,

Yup, I've heard about these, they sound like a worthwhile upgrade.

I also just heard about a Master Tach. Its available here

It looks like an analogue tach. But @ $185 its another step up...

Tachometer
 

No modeler need a $185 tachometer.

The Hobbico (which I have), Glowbee and any other photocell optical tachometer, will do the job, as long as the batteries are good and you know what you are doing.

Always use the tachometer in sunlight. Any artificial AC light source flickers and my Hobbico measures even an incandescent source.

Tach the prop from behind, with the sun in front of you, whenever you can.

Check zero, with engine off. If there is a reading, something is wrong.

Never try to tach your engine, when close to high-volage power lines. Readings will most likely be wrong.

If your engine is idling and you read 31.4K RPM, it is wrong.
You must know what range to expect before reading, even by sound frequency alone.

Point the tachometer at mid radius. If the prop is 12" in diameter, point it about 3" in from the blade tips and from 4-12" behind the prop (or in front of it, if you must).

Never point the tachometer at the spinner, or too close to it. The results will not be real.

If your engine is supposed to be around 17K and you see 22K, or 25.5K, the tachometer is lying to you...

If there are props turning in the background, readings may be wrong.

Like the LTI 20/20 police laser speed gun, if you point it at a tree and it reads 22MPH... something is wrong.

Sincerely,

Hangar9 MiniTach
 

I've been using the hangar9 minitach. Works really well, much better than the red globee garbage. Wanted to get a TNC tach but it was too expensive (anyway it seems to be superior...)

WISH I HAD SEEN THESE POSTS SOONER...
 

Hi guys,

Was just out tearing my hair out with my new Glo Bee tach. It just won't read right. Bright sunlight, but with a grey APC prop. Maybe that's the problem. RPM's are unrealistic, and jump all over the place from way too high to way to low. Dusted off my old analog ACE tach, and it reads dead steady. That poor old tach has been through hell, and still works great. I thought I was being cool and buying a GOOD digital tach in the Glo Bee, as I'm doing some experimenting and wanted reliable results. Damn....

Should I try dusting a coat of paint on the prop? White or Black?

How much is a "TNC" tach, and where do I find them?

Thanks,

AV8TOR

Glowbee
 

Av8tor1977,

The Glowbee you have is probably a lemon.
Any of those I saw gave a correct steady reading, when it was used right.

Sincerely,

what tach are you using?
 

Yeah, that must be it, as this thing is impossible. I just painted the back of the prop, pointed the engine into the sun perfectly, and with the tach held EXACTLY A CERTAIN WAY, well above and behind the prop, it would agree with my other tach for a few BRIEF moments. Other than that it was all over the place.

Major bummer as it is a true hassle to send things back anytime, but especially from here in Mexico.

Thanks,
AV8TOR

what tach are you using?
 

Av8tor,

Sending things back in Israel is harder. When you buy it you pay customs. When it is sent back to you after repairs, you pay again....

You got to make sure it is good before bringing it. Sometimes it is impossible.

Sincerely,

what tach are you using?
 

In the USA, we point our tach at a flourescent light. I think 2 blade reads 24, and 3 blade reads 36. It's a decent benchmark to calibrating.

what tach are you using?
 

Yes, you can use a light to check calibration on them. Actually any household light will work; it doesn't have to be flourescent. It is due to the cycling of the alternating current at 60Hz, which causes the tach to "see" 3600 rpm's. (Our electric lights turn off and on 3600 times a minute, we just can't see that!)

This tach is bad. After dark, I set up a battery powered search lamp/spot light directly in front of the prop and the tach would still not read properly. It's odd, because it will read household light properly as in above. It will almost read idle rpm correctly if you hold it just a certain way, but goes nuts at any thing higher.

I contacted Glo Bee and they said it must be bad and would have to be sent back.

Bummer, as that's not so easy to do from here in Mexico. Oh well...

Thanks for the input,
AV8TOR

what tach are you using?
 

Yup, you're right about the diagnostics. I don't remember all the figures for 2,3 or 4 blades but I recall my instruction book says hold the tach up to a fluorescent light. I've not tried it with an incandescent light (bulb).

The test doesn't actually prove much. Just that the circuit and photo sensor is working. Being digital, there's not much to go wrong, either it works or it doesn't. I doubt if a standard digital hobby tach can go out of adjustment.

Holding the tach about 2" in front of a light satisfies both conditions for the tach to work. Plenty of light and a stable pulse.

In real conditions ie taching a prop, there are many variables. There's the available light and the contrast offered by the prop. EG taching a gray APC prop in cloudy or dark conditions won't give enough contrast to allow the sensor to see the prop.

For the battery lamp/torch/flashlight method to work you need to hold the lamp on the opposite side of the prop directly facing the tach.

These tachs really work best in decent sunlight were the tach is facing the light, not in shadow....

The good news is, in Mexico there should be plenty of bright sunlight :D

what tach are you using?
 

Yeah, that's what I did. I had a million candlepower battery powered search light position perfectly behind the prop, with me doing the checking in front. No dice. That HAS to be a good enough condition for it. I even painted the prop.

I also tried it at all kinds of angles in the bright sunlight to no avail either. This tach is bum! Glo Bee agrees, so back it goes...

Thanks,
AV8TOR

TNC tach
 

Get the TNC at http://www.bktsi.com/TNC/pt.htm

After going DIGITAL, Tiggerinva, there ain't NO way I'm goin' back to ANALOG tachs...
 

Dear Tiggerinva:

The PIPE Here again-these days I'm using a Futaba digital readout "TachoTimer" that I still have from my previous period (1977-1986) in the RC hobby, and I've seen a GOODLY number of tachs, both digital AND analog, in the past-and there's NO way I'd EVER go back to using an ANALOG tach again!

The "TachoTimer" was even featured WITHIN some of the top-end Futaba transmitters nearly twenty years ago, and a corded sensor was plugged into these transmitters to use that feature.

And amazingly enough, GORDON ANDERSON, the creator of the MicroStar computer chip based RC transmitter encoder board, has done likewise with his MicroStar, in including a tachometer circuit within his radio board-and directions are available at his site [ http://mstar2k.com/ ] on how to make up the cable and sensor housing to get that tachometer display in HIS radios-heck, where I'm building up a near half-dozen of these myself (MicroStar based SINGLE STICK transmitters) I may even build up a corded tachometer sensor for MY "knobby" M*2K radios!

Sorry to disappoint you, but that "Master Tach" you mentioned seems to be just a "warmed over" version of a VERY similar multibuttons-for-range tach put out LONG ago by the Colorado-based Royal Electronics, now long out of business! Other notable (and simpler and a bit less accurate) analog tachs were from Heathkit, known as "the Thumb Tach", and Ace RC (the "TachMaster").

For my FOUR STROKE engines, I'd still prefer the accuracy of what I hope to soon be able to purchase-the TNC SensiTach model PT10S-as it apparently seems to have a usable 5 RPM sensitivity, and where I don't run my engines very "fast" (I just LOVE big, slow-turning props) the PT10S model's accuracy seems to be just what I'm looking for!

So I STILL prefer the accuracy advantage that DIGITAL tachs have over analog ones-and especially over one that seems like a re-incarnation of the old Royal Electronics multibutton analog unit of SO long ago!

Yours Sincerely,

The PIPE! ;)

what tach are you using?
 

Shop around and find a Ace Tachmaster analog tach. Works great, analog reading is steady, and if you look you can usually pick one up for $25.00-$30.00

what tach are you using?
 

The Pipe,

Thanks for the informative post. I wasn't particularly advocating the use of the Master tach, I just happen to have found a link to it and thought it might be of interest.

As for the current crop of 'hobby' digital tachs, they all seem to be much the same in that I've heard of people with difficulties with various models in respect to getting a reliable reading. This is in line with own experience with my H9 tach.

The TNC tach seems to be the exception, its certainly on my list of useful accessories...

Where to buy TNC
 

Used to be that the TNC was only available from Tony directly. That's how I bought mine 2 years ago. I had heard that Tony's health was not good and that he has stopped producing them. However, Don's Hobby Shop has been advertising them recently in the magazines. $99.

http://www.donshobbyshop.com/

You will have to call, as Don's website does not show much in the way of product.

I also have a Magnum tach, which is similar to the H9 with the angled display. It works very well, as long as you are pretty close to the prop. The TNC is a bit more stable, and it can read from further away. By pressing a button on the side, you can have it display an extra digit, down to 10 rpm resolution.

A great investment and well worth it.

For either tach, when the sunlight is getting low, or even at night time, I simply aim a large battery operated flashlight on the front of the prop (in front of the engine) and stand behind the prop with my tach. Works extremely well.

Here's the NEW TNC home page...
 

Dear Fellow RCU'ers:

The PIPE here yet AGAIN-and at http://www.bktsi.com/TNC/tnc.htm is the NEW homepage for Tony Criscimagna's TNC tachometers!

I'm STILL hoping to be able to save for ONE of the PT10S models by late this summer...would surely be VERY much worth it for my growing hangar of four stroke engines!

Yours Sincerely,

The PIPE! ;)

RE: what tach are you using?
 

TNC Is Not Dead! Fromeco http://fromeco.org has purchaced the rights to TNC and is currently building The new and inproved TNC Tachometer. It is an enhanced version of the origional TNC. I should be receiving a pre-production model this week and testing it this weekend. Cost $95 Should be avalable First Week in September

http://www.rcuniverse.com/forum/upfi...37/Mk27547.jpg