View Full Version : Thorens speed control
I would like in the new year to remove the mechanical speed adjuster from my Thorens TD160 and replace it with an off-board control.
Does anybody know of a thread for this, I've tried searching.
cheers
bobbasrah
21-12-2011, 14:19
Barry, I suspect you may find some under Linn or similar models of Thorens, google it as I did with variations.
There are two versions that I found previously, both DIY frequency control over 110v ac, similar to the Origin Live design.
As I was initially looking to drop the voltage on a 160 when I came across these PSUs, but they as they were geared to what you were after rather than voltage reduction I paid them no mind. I'm tempted to go a similar route, but the detection side seemed a mite complicated.
If I find them again I'll post back.
There's a DIY speed controller at the final stages of development over at Lenco Heaven (PCB has been designed and a few members are currently beta testing and ironing-out some issues). This will allow voltage reduction and one, two or three adjustable speeds depending how you build it.
http://www.lencoheaven.net/forum/index.php?topic=4406.0
Reid Malenfant
21-12-2011, 14:48
The problem with voltage reduction is a huge drop off in torque, really the frequency needs altering to get the best out of a syncronous motor.
It'd still work mind you, just not as well as changing the mains supply frequency.
It shouldn't be too difficult to cobble something together with an low distortion oscillator (with a switch to control the frequency), an amplifier & a capacitor & transformer to step up the output to 230V ;)
Hi Mark,
The Lenco Heaven one works by changing the frequency. It also (optionally) allows voltage reduction to enable the optimum balance between motor vibration/noise and torque to be found.
Reid Malenfant
21-12-2011, 14:54
Ah, much better :) Cheers for putting me right, I guess I should have taken a look before typing :eyebrows:
S'all right Mark, and thanks all for the links, as I should like to have a go at some point..
The synchronous motors Thorens used gave just about the correct torque in their designs I thought, but an external smoothing and filtration transformer a la Naim Armageddon "may" be all you need. Don't forget the circuit used in the TD125 series either, as this allows smooth motor rotation and is three speed (I'm sure the 16rpm could be dropped and a 78 option introduced if necessary, though not sure how the belt itself would cope?)
The Lingo used to give full power to allow starting, which was then cut back to around 70 or 80V for running proper, this removing much of the motor vibration from the deck-plate. I don't honestly think the TD150/160 series suffered so tbh, so a simple frequency shifter for the two speeds would be ideal.
Re Lenco's. I now have my GL78 project to start in the new year and a facility to safely take the motor torque back a tad would be ideal for these as previous attempts with fixed inline resistors reduced motor borne "rumble" by around 10db I believe, a useful amount on an already fairly quiet motor system of the type. The only Lenco difference I found (nothing sonically to me) was the sharp "kick" on startup was reduced to something more idler-friendly I remember...
Reid Malenfant
21-12-2011, 15:55
Hi Mark,
The Lenco Heaven one works by changing the frequency. It also (optionally) allows voltage reduction to enable the optimum balance between motor vibration/noise and torque to be found.
Just took a look & it's kind of what I fugured, I couldn't find a circuit diagram though :scratch:
Would have been nice to see that in all honesty ;)
It would have been nice if they had used the output of the transformer as part of the feedback loop to gain rock solid voltage stability. That could easily be implemented with an extra opamp between the oscillator & amplifier input. Obviously this wasn't done or the output voltage wouldn't have dropped as it appeared to.
Why didn't the guy have a frequency counter to accurately set the thing up???
Still a noble effort none the less :)
Now THAT's a Christmas challenge Mark - and if you're serious about giving up smoking, then it might be something to keep you occupied :D
Just took a look & it's kind of what I fugured, I couldn't find a circuit diagram though :scratch:
Would have been nice to see that in all honesty ;)
I think Nigel wants to get it all pretty thoroughly tested and idiot-proof before publishing the circuit and parts list - many of the people who have expressed an interest in building it on LH have done little or no electronics DIY before and safety etc seems to be his overriding concern - so he doesn't want any of them trying to build it before he's done comprehensive and easy to follow instructions complete with appropriate safety warnings and so on.
As to the circuit design choices etc. - I've no idea...
Reid Malenfant
21-12-2011, 16:09
I am going to give up smoking when my tobacco runs out, yes ;) I have been ordered by my doctor to give up drinking to, which I said I'd do when the 3 crates or so run out :D
Honestly it was a good job I went to the quacks about those occular migraines as I'm not very healthy at all :rolleyes:
High blood pressure, high cholesterol, high triglycerides, depressed liver function, high salt in my blood :mental:
I guess I can look forward to a much healthier year ahead, & I only decided to give up the drink & ciggies to get things done :rfl:
Looks like I need to before I kick the bucket, let alone get things done :eyebrows:
I do like the way he's carefully suited and booted all the mains connections. Many HiFi products, especially those of yore, would have done well to do the same...
I wonder how good Alex is with metalwork? What with my soldering (in)experitise :) and hopefully a "crafty" bloke who can do the cuttin' n drillin' we may be able to make up a couple at least for Garrard, lenco and Thorens use :)
Reid Malenfant
21-12-2011, 16:12
I think Nigel wants to get it all pretty thoroughly tested and idiot-proof before publishing the circuit and parts list - many of the people who have expressed an interest in building it on LH have done little or no electronics DIY before and safety etc seems to be his overriding concern - so he doesn't want any of them trying to build it before he's done comprehensive and easy to follow instructions complete with appropriate safety warnings and so on.
As to the circuit design choices etc. - I've no idea...
All very sensible imho...
Perhaps I simply should have asked if there was anything up there, I honestly didn't consider what you just posted ;)
I am going to give up smoking when my tobacco runs out, yes ;) I have been ordered by my doctor to give up drinking to, which I said I'd do when the 3 crates or so run out :D
Honestly it was a good job I went to the quacks about those occular migraines as I'm not very healthy at all :rolleyes:
High blood pressure, high cholesterol, high triglycerides, depressed liver function, high salt in my blood :mental:
I guess I can look forward to a much healthier year ahead, & I only decided to give up the drink & ciggies to get things done :rfl:
Looks like I need to before I kick the bucket, let alone get things done :eyebrows:
Oh cr@p... I wish you well. My bloods are much better now I'm on meds for the T2 Diabetes and it's got to the point that if I od on cake or mince pies - cough - I feel ill afterwards for a few hours until the blood sorts itself out..
I wonder how good Alex is with metalwork? What with my soldering (in)experitise :) and hopefully a "crafty" bloke who can do the cuttin' n drillin' we may be able to make up a couple at least for Garrard, lenco and Thorens use :)
Dave, it may well be an idea to put your name down for some PCBs at LH (around £5.50 each + P&P) sooner rather than later as I don't know when the list will close or if there will more than one production run. The thread for requesting being added to the list is linked to from the first post in the link I've quoted above.
Also, I don't know when Nigel will get the project finished as he's busy with work and it's all stalled a bit at the moment.
I am going to give up smoking when my tobacco runs out, yes ;) I have been ordered by my doctor to give up drinking to, which I said I'd do when the 3 crates or so run out :D
Good luck with that Mark. I'm going to reduce the amount I drink in the New Year too (luckily, I never took up smoking) as I drink every night - and that is going to have to stop.
Reid Malenfant
21-12-2011, 17:18
Good luck with that Mark. I'm going to reduce the amount I drink in the New Year too (luckily, I never took up smoking) as I drink every night - and that is going to have to stop.
The drink shouldn't be a problem, I gave up for a week last year due to the meds I was on. A few nights of disturbed sleep & it was all over & done with ;)
The ciggies are a different matter though :doh:
Best of luck to you to Keith.....
Back to the speed controller :D
I wonder how good Alex is with metalwork? What with my soldering (in)experitise :) and hopefully a "crafty" bloke who can do the cuttin' n drillin' we may be able to make up a couple at least for Garrard, lenco and Thorens use :)
Always up for a challenge! (And if not, I have a very talented dad who IS good at metalwork - he used to make reproduction suits of armour, and historical/fantasy weapons - but that's another story.)
(Nearly 2 weeks without a ciggie here - I'm using a patch, and it has been fine until today when I could kill for one! I've got 1.33 kids to worry about, so I will be ditching the booze in the New Year (already cut right back, nothing in the week usually, but make up for it at the weekends! :eyebrows:) Good luck Mark and everyone else - it is tough, but worth it at the end of the day - another acquaintance of mine in his early 40s had a stroke a few weeks back - he'll be ok, but certainly made me think as I drink/smoke more than he does! :eek:
Maybe we should start a "New Year's Resolitions" thread... Sorry Barry! :o
God I've just logged on and panicked when I saw all the replies, glad they were off topic as now I can put a bit more to what I want and can do.
Right I'm a total novice at electronics, in fact I'm not even that. But I am handy mechanically. I was wanting to buy a smart looking Project Speed Box type of thing and someone tell me which wires to connect and which bits to chuck away.
Please :)
Reid Malenfant
21-12-2011, 18:27
Find a circuit diagram of the thing & you might be in business ;)
Cheers Mark, circuit diagram of the speedbox or the Turntable ?
Reid Malenfant
21-12-2011, 18:43
The speedbox, the TT should be as simple as breaking eggs ;)
bobbasrah
21-12-2011, 18:45
Didn't realise your avatar was you trying to open the last superglued pack of tobacco Mark....
Must look into that LH controller further, looks interesting.... Can it be improved as you suggested Mark?
What?
Reid Malenfant
21-12-2011, 18:59
Didn't realise your avatar was you trying to open the last superglued pack of tobacco Mark....
Must look into that LH controller further, looks interesting.... Can it be improved as you suggested Mark?
:lolsign: @ the tobacco thing :eyebrows:
Yes I don't see why not. You see the transformer only needs to supply the relevant voltage & frequency that the control circuitry is feeding the amplifier - which feeds the transformer. Effectively the transformer is out of the feedback loop, but it could be part of it. A single or possibly dual opamp in between the frequency generator (which will have a fixed or variable voltage) & the amplifier could compare the frequency generator output & the transformer output, if they don't match then the opamp would force them to & thus the transformer would then be inside the feedback loop.
It'd probably be safe to have feedback up to 500Hz, maybe 1KHz which in reality is all that'd ever be needed as that's way above the mains frequency that you'd be feeding the synchronous motor.
I think I'd be more interested in seeing the oscillator that is generating the sine wave though & how stable it is.
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