Depac tach signal generator

[NormS]

Obtaining a replacement tach signal generator for my Depac data acquisition system, has proven to be more difficult than I expected. Another company in Wisc. bought the Depac stock after Dave Manzolini died, and that company is so far refusing to sell me another tach signal generator.
No one that I know of, has figured out where these tach generators were made, but I suspect either Europe or Japan, as they were obviously built
where the metric system is used. I'm looking for another source for a compatible tach generator that will work with the Depac system.
Anybody have some suggestions on where to look? Norm/CFS

[tenxal]

Obtaining a replacement tach signal generator for my Depac data acquisition system, has proven to be more difficult than I expected. Another company in Wisc. bought the Depac stock after Dave Manzolini died, and that company is so far refusing to sell me another tach signal generator.

What's their reasoning on refusing to sell you one?

[cnsperf]

NormS,

Are you referring to the encoder on the water brake or the electronic tach itself? Also, do you know if yours is 50 Hz (SuperFlow) or 60 Hz (Stuska)? I may have the Hz/brake manufacturer mixed up as I am going from memory and don't have access to notes at the moment.

Chris

[NormS]

I know that it puts out 50 pulses per revolution , and about
16 volts AC per thousand rpm. It has a 5mm shaft, and the rest of the dimensions are metric too.

[cnsperf]

Okay. That is the 50 Hz encoder. Let me see what I can dig up for you.

[NormS]

I think the reason for not selling me one, is that he has a limited stock and does not know where to get more of
them. Neither do I , so far.

[NormS]

Hopefully, cnsperf may have something to solve this problem

[NormS]

On the subject of the lack of service to people that already have Depac systems, does this mean that someone who buys a complete Depac system now, from this company that bought the Depac stock, is on their own after that? I don't know. If this is the case, they may sell very few systems, and only to those customers who don't realize what the situation is. Sad situation. Even though Dave Manzolini was a bit difficult to get along with, his service was much better than this.

[BillK]

Norm,
First of all what is wrong with yours ? It may be repairable ? Can you post a picture of the item ? From my previous electronics experience I have found that a lot of those types of parts are pretty generic and by doing a little searching you can find them.

[NormS]

Hi Bill, There are two failure modes for these signal generators. One is that the 50 tooth wheels on the main shaft are only held on by a press fit, and over time, the heat and vibration of use causes them to lose that press fit, and spin on the shaft. I've fixed that by making a new main shaft with a flange on it, and using 4-40 cap screws to hold the wheels, and the high strength ring magnet between them, to the flange.
The second mode is a failure of the delicate windings in the stator. That I don't know how to repair. The press fit issue of the wheels seems to be the common mode.
Please send me a number in a private message, where I can text you some pictures. Thanks, Norm

[cnsperf]

I think it is a stepper motor. Try a google search for rotary pulse generator or stepper motor. Might want to include 5 mm shaft to narrow down the results.

Chris

[Circlotron]

Yeah, stepper motor. They will work quite well as a tacho generator. You can often find ones second hand dirt cheap or free. Look inside a discarded office printer. A common specification is 200 steps per rev so I’d guess that translates to 50 cycles per rev.

[NormS]

Now that I look them up online, what I have sure looks like a NEMA17 size stepper motor. What is confusing, is that the steppers I find online , have at least 4 wires. The Depac tech gen has 2 wires, and doesn't appear to have ever had more than 2 wires. I read online that there is no such thing as a 2 wire stepper. Maybe that's wrong, I don't know yet.

[NormS]

If I were to use a 2 phase stepper motor(4 wires), would I just use 2 of the wires to use 1 of the phases? If that actually put out a signal, would the pulses per revolution be half of what the motor would put out, with both phases being used? When I call around, I'm getting a lot of "I don't know"s. Dave Manzolini told me years ago, that the Depac system requires a 50 pulse per revolution tach signal.There are so many variations in the available stepper motors, figuring out what to get, is getting pretty difficult. What the internal design of a stepper motor needs to be, to put out 50 pulses per rev as a signal generator, has still not been defined, at least for an electronics challenged guy like me.

[cnsperf]

Norm,

The one I have on my dyno is a four wire, but it only uses two of the wires.

Chris