[sdiy] Echolette Echo 400 / Dynacord EC-504:: Anyone have a varispeed mod figured out?

[Ben Stuyts]

Correct, and there are ready made frequency inverters which can do this. I use those at work. However, they usually chop up the output (PWM) at frequencies of a few kHz. You would need to very heavily filter the output to make sure that this won’t be audible. For example:

https://nl.farnell.com/schneider-electric/atv12h018m2/drive-v-s-atv12-240v-0-18kw-1ph/dp/2042992 <https://nl.farnell.com/schneider-electric/atv12h018m2/drive-v-s-atv12-240v-0-18kw-1ph/dp/2042992>

Ben


> On 26 Sep 2020, at 13:27, Richie Burnett <rburnett at richieburnett.co.uk> wrote:
> 
> That AC motor with run capacitor attached looks like either an induction motor or a salient-pole synchronous motor. I suspect that you will have limited success trying to control the speed with a light dimmer. The Triac switching an inductive load will probably also generate a lot of switching noise and EMI.
> 
> In order to properly control the running speed of the motor you'd need to alter the frequency of the AC supply to the motor. If you decrease the frequency you may also need to decrease the applied voltage in the same proportion to prevent it drawing too much magnetising current and saturating.
> 
> Hope this info helps, 
> 
> -Richie,
> 
> 
> ---- Kenny Balys wrote ----
> 
>> 
>> Further info:
>> 
>> This echo machine has a 220V AC motor, not a DC motor.
>> 
>> What I think I might do is something like an AC light dimmer
>> triac thing. Like this:
>> 
>> https://www.electroschematics.com/motor-speed-regulator-with-triac/
>> 
>> The goal is to slow it down so that I can get longer delay times.
>> 
>> The 75, 150, 225, 300ms delay times doubled would be just awesome.
>> 
>> Hope this isn't OT. Thanks in advance for any input.
>> 
>> 
>> On 26.09.20 24:43 , Kenny Balys wrote:
>>> 
>>> I am thinking about adding a varispeed control on my Echolette 400 tape delay.
>>> 
>>> The partial schematics are available here: (look for Dynacord EC-504, its the
>>> same as Echo 400)
>>> http://peel.dk/Dynacord/index.html
>>> 
>>> The details of the motor control seem to be missing.
>>> 
>>> Has anyone done this?
>>> 
>>> If so, I would love to hear how you did it.
>>> 
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>>> 
>> 
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