Tachometer

[Les Toombs]

Does anyone know where to buy an "inexpensive" Tachometer
- to check speed of motors/gear reduction/paddle wheels?

OR does anyone have (or know where to get) plans to build a
Tachometer?

[John Roberts]

Tower Hobbies, (1-800-637-6050) www.towerhobbies.com, has a Globee Intellitach LCD digital Tachometer, stock no. TC3620 priced at $27.99 in their latest flier. Thsi is intended for model aircraft, but might suit your purpose. Worth checking out.
Hope this helps.
John

[Les Toombs]

Thanks.

I'll have to figure out if I can use this type tach to measure
motor/gear/paddle RPM's.

Maybe a mechanical linkage would be better.

Anyone else have any ideas??

Thanks again.

Les Toombs
Brandon, FL

[daniel Munoz]

if you can deal with a little magnet fixed somewhere, and some final
mathematical computations to retreive the correct value (adapting mile/hour
or km/hour to RPM), a simple and very cheap bicycle speed/distance odometer
could do the trick. I guess paddle wheels are not turning faster enough to
overload those odometers.

Daniel.

[Paulrjordan]

Hi Les:

This is almost an identical question I asked a couple of weeks back
in my post #356 to Ken, the owner of paddlewheels UK, who supplies
all kinds of model electronic gadgets and special FX and is also an
avid paddlewheel builder and PADDLEDUCK! Visit his website at

http://www.paddlewheels.co.uk

Ken immediately replied to me in a personal email and told me about
an optical tachometer he uses..but couldnt remember where he bought
it. Last week he found the receipt and emailed me.

>> Hi P.J,
>> I was having a clear out and low and behold ,I came across
>> the reciept for my O.D.T. Jan 2000 price £24-95 purchased from
>> Slough Radio Control Models.

I then asked Ken how he has modified it for paddlewheelers and R/C
boat applications. I received his reply this afternoon (which is
rather timely in view of Les's RFI)

>> Hi P.J.
>> I just knew you were going to ask! Well it has taken me ages to
>> perfect a method of doing just that. First ,with 3 or 4 blade props
>> no problem you just adjust the unit { the one I have anyway}to read
>> the appropriate number of blades. It's designed for airplane props.
>> Second Motor shafts.
>> I've made an adapter to suit the motor I use that fits in the
>> output shaft to look like a very short blades prop. Again it reads
>> the same as before.
>> Third. Paddle Wheels.
>> Here's the clever bit.I've just cut a card disc. It must be black
>> card, then with a white permanent marker I drew a line 3mm thick at
>> 120 deg intervals. Fix the disc to the side of the PaddleWheel with
>> double sided tape securely then it reads it as before. If you have
>> a problem reading the first two just highlite the leading edge of
>> each blade with the white marker. I have been using this method for
>> quite a while and it works well.I hope you find this info useful.

Well, you're not kidding, Ken. I whooped for joy when I saw this and
I think we may now have a decent way of figuring out the three types
of RPM we're looking for SHAFT, PROP, and PADDLEWHEEL.

Thanks a million for this, I'm sure a number of modelers will find
this principal useful. I KNOW I will as I've been wrestling all week
with the revs on a motor which I've had to GUESS at..and it's the
ONLY unknown factor in a motor/gearing/current problem I'm trying to
solve.
(I know we gear down...but how bout gearing UP?)

I also notice John's (Roberts) posting today which will be of help to
us North American Paddleducks and in which he writes:

> Tower Hobbies, (1-800-637-6050) www.towerhobbies.com, has a Globee
> Intellitach LCD digital Tachometer, stock no. TC3620 priced at
> $27.99 in their latest flier. This is intended for model aircraft,
> but might suit your purpose. Worth checking out. Hope this helps.
> John

Well, it certainly does, John, as I think we may be able to adapt
Ken's principles to the Intellitach.

With all your help, we're getting closer on this one...and that is
what this forum is all about.

Thanks to you all

PJ