Hi guys, I've been busy, sorry for the delay and thank you again for your answers.
I want to reduce the speed to have a longer delay, that's is.
How much I want to reduce it? Half speed (more or less) it would be enough, and I don't care if it is fixed on half the speed, don't need a potentiometer.
I think that buy another motor isn't an option attempting to money and time.
Thanks!

 

If not meant for me, why quote me?



So you don't think "small rapid variations in speed"(your own words) would make a warbling sound from a tape?

An unstable drive will do that, but there are drives that do not deliver those rapid variations on speed. And looking at the picture of the system it seems that there is enough material rotating to have enough inertia to prevent any speed variation. Driving the motor with a lower frequency would not cause speed variations unless the system had way too much friction.

 

Hi guys, I've been busy, sorry for the delay and thank you again for your answers.
I want to reduce the speed to have a longer delay, that's is.
How much I want to reduce it? Half speed (more or less) it would be enough, and I don't care if it is fixed on half the speed, don't need a potentiometer.
I think that buy another motor isn't an option attempting to money and time.
Thanks!

If you want a longer delay the easy way is the old way that audio echo machines worked. You just move the play back head farther away from the record head. Many of the old ones had several playback heads that could be selected with a switch. Or one head that could be moved along a slide track.

One link of many that explains it - https://reverb.com/news/how-to-make-your-own-tape-delay-using-an-old-reel-to-reel From Google with many more - https://www.google.com/search?client=firefox-b-1-d&q=diy+tape+echo+machine

 

Another option may be to lengthen the tape path between the record head and the playback head. That would be a mechanical change and not require any electronics or motor alterations at all. Possibly adding a couple tape guide posts taken from a scrapped VCR, which usually contains some tape guides. That would be a simple and cheap alternative that will not change the frequency response like slowing the tape will do. But it might not be possible. It is certainly worth investigating.

 

Thank you, but it is not possible, what I wanted to know was if it is possible to reduce motor speed, because I tried different methods and I couldn't.
Sorry, MisterBill2, but I don't know what you mean with "An unstable drive will do that".
The machine is the Dynacord mini echo.

 

Thank you, but it is not possible, what I wanted to know was if it is possible to reduce motor speed, because I tried different methods and I couldn't.
Sorry, MisterBill2, but I don't know what you mean with "An unstable drive will do that".
The machine is the Dynacord mini echo.

By "unstable drive" I mean a speed control that oscillates, usually because of incorrect feedback in the circuit or because of incorrect adjustment. Many speed control systems measure speed and adjust their output to hold the speed steady. Those can oscillate if they are not adjusted correctly.
But now I think that extending the length of tape between the record and play heads id the way to go.

 

But now I think that extending the length of tape between the record and play heads id the way to go.

Gee wonder where that idea came from?

 

OK, one more possibility that would certainly work, but will be totally not reversable. That is to have he motor shaft diameter reduced in the section that drives the tape. If you cut the circumference in half you cut the surface velocity in half, and double the delay time. But you will need to have the shaft centerless ground at a good machine shop, since anything less than perfect will cause speed variations, or problems with the tape not pulling straight. But it would be simple and effective. But cutting the tape speed in half will effect the high end of the frequency response and so you need to consider that part of the results.

 

The machine is the Dynacord mini echo.

The delay is adjustable, it looks like by sliding the play head along the rail. It is shown in the manual, although it is written in German, the picture shows it very well. Item #23 is the play head, item #25 is the rail it slides on and item #18 is the record head.
http://www.peel.dk/Dynacord/Echocord_Mini.html

 

Thank you for all your replies.

I was looking for an electronic solution. If it's not possible okey, it's a pity.

I don't want to half cut the motor or buy another one or some other mad solutions.
Yes, I know how my delay works.

 

Thank you for all your replies.

I was looking for an electronic solution. If it's not possible okey, it's a pity.

I don't want to half cut the motor or buy another one or some other mad solutions.
Yes, I know how my delay works.

Read the reply #29 by shortbus. Unless the delay is already adjusted to maximum it is what you are looking for. As for simply slowing the motor, it occurs to me that there is a circuit that was used for business phone applications that somehow produced 90 volts at 20 Hz from the AC line. Since that arrangement is quite obsolete now there may be some of those modules available someplace, or at least some information on how it was done.

 

Hi folks!
I found a new item that maybe could work.
What do you think?

https://www.amazon.es/Controlador-V...=motor+220v+dc&qid=1573909173&s=tools&sr=1-10
Thanks

 

That controller seems to be for a DC motor, not AC.

 

Yeah, that appears to be the same controller as shown in the first posts, just that a bridge most likley added for DC motor.
If so, it won't work with this motor.
Max.

 

I recently read a posting elsewhere that showed how to use an audio amplifier as a variable frequency power source. Simply feed the amplifier a signal and use a transformer to boost the output voltage to that needed for the application. If you know the approximate wattage of the motor that is the size of amplifier that you will need. The post that I saw used a 24 volt transformer with the 24 volt side connected to the amplifier output and the 120 volt side connected to the load. That should work in this application also, at least as an experiment to see if it produces the desired results.

 

I'm no motor expert. Since the motor winding reactance will decrease with frequency, motor current will increase. Won't that risk the motor over-heating unless it's designed to cope with a vfd drive?

 

With an experiment it is usual to pay attention to things like heating, and also current. In this sort of experiment the process would be to lower the driving voltage to see the minimum that wouold provide adequate speed stability. This was not intended to be a suggestion for blindly bashing away at an issue.