60 WPC Amplifier for DIY Turntable Motor Drive

[carsoni]

Thanks Ralph. I’ll make that payment in a moment. Can I use the email address you use for PayPal to send you the address? I’d prefer no to dox myself accidentally!

 

[carsoni]

@ralphfcooke

Shipping address is probably attached to the PayPal payment. Let me know if it isn’t there.

 

[ralphfcooke]

Thanks Ian, I'll get them in the post to you today. Please let me know when they arrive.
Regards
Ralph

 

[carsoni]

Brilliant! Thanks mate.

Having a thought about using a raspberry pi to act as a PID controller for auto speed management.

The idea (if it has legs?) would be to drive the Up and Down switch inputs low from the pi to change the frequency and use a Hall effect or optical sensor in the feedback loop.

Worth pursuing?

 

[ralphfcooke]

I think that's been done using an arduino, have a look here
https://www.diyaudio.com/community/...-for-record-player-lcd-display.301609/page-25

 

[carsoni]

Thanks. Looks like a good starting point.

 

[rif]

if I'm understanding your question, you're asking if the up/down/standby buttons can be controlled by another means? yes they can. the buttons just pull the line to ground.
I have ine controlled 3 ways: the pcb buttons, the rotary encoder, and 3 IR controlled relays.

https://www.diyaudio.com/community/...for-turntable-motor-drive.298018/post-7266980

 

[Enby2]

Yes it is a dual phase motor, and you could happily drive it with a stereo amplifier or modules, along with a couple of transformers to get the output voltage back up to 110v or so. Most people use class D amplifiers as they are a lot more efficient and don't need much/any heatsinking. The Hurst is a low power motor, and you would only need around 20VA transformers, and a couple of 60watt amps. Something like these should do the job
https://www.ebay.com/itm/323772896631
You need the extra power in the amps in order to manage the startup current into the transformers.

Thanks for the response! I am wondering if it matters whether the input is DC rather than AC on the amps? As it seems those run on DC, does that mean I would need to wire them up much differently than in Pyramid's guide?

 

[hvalreki]

I am ready to run my Papst motor in 3-phase. It lives in my Fairchild 412-1A, model Papst HSM 14.50-4-675D. I live in Europe and am ready to upgrade my farmer-bodged pulley to compensate for the 50Hz.
I have been following these discussions for years and noticed that several of you—Ralphfcooke, twystd, and Pyramid use the SG4 to run these Papst motors in 3-phase. Can you tell me if there is any thing more that I would need aside from:

SG4 kit

3 channel 200W CLASS D Amplifier Board which Ralphfcooke linked earlier

3 x 60VA transformers for powering each phase

Thanks !

 

[uptick]

60VA x3 90VA iron for a 7VA motor?
Are you cutting lumber?

 

[hvalreki]

This was the setup which worked for Ralphfcooke
I think he even made a version with more iron, but that required a full time fan.

 

[uptick]

Look at the size iron of the motor, same voltages and frequency, for clues to appropriate size cores.

Only use toroidal transformers, which have a much smaller stray fields, not zero but better. EI, L, C, R-core, Flat pack etc not so happy. I have the latter, thinking about making new PCB for potted toroidals, maybe even remoting those in a steel box. Nobody advertises stray field or leakage current numbers for their transformers. Line frequency leaks thru transformer insulation, I had to go thru a pile of wall-warts to find a low leakage one. Measure AC current to power company neutral/ground to the DC output.
I want as little as possible 60Hz magnetic or electrostatic fields around my "pickup".

 

[Pogany]

Dear Ralph
I want to buy
2 SG4 ICs and 2 associated PCBs if available.
Please send me the cost of shipping to Hungary.
It would be urgent!
Andrew

 

[Paulo Batista Gomes]

Hi all,
60W LM3886TF Sound Audio Amplifier 2-Channel Digital Power AMP | eBay
The link to the amplifier indicated at the beginning of this thread is no longer available, can someone please suggest a replacement for it?
Thanks, Paulo

 

[glenv6]

Hi @Paulo Batista Gomes - Here’s the amp I used, still available on Amazon…

https://www.amazon.com/gp/product/B01CZQAFCO/ref=ppx_yo_dt_b_search_asin_image?ie=UTF8&psc=1

 

[Paulo Batista Gomes]

Hi @glenv6
Thank you very much for your recommendation.
Apparently, there are many suitable amplifier options then!
However, I still have some doubts, in the indicated amplifier, there is an indication for replacing 2 resistors to adjust the gain, and there is also an extra connection, which I indicated on the right edge, are these important?
Paulo

 

[glenv6]

See post #46. You won’t need to alter the gain of the TDA7492, but you will need a voltage divider between the SG4 and the input to the amplifier.

 

[Paulo Batista Gomes]

In the example in post #46, in the case of a 2 phase motor, connect outputs 1 and 2 of SG4 to inputs R and L of the amplifier independently, correct?

 

[glenv6]

Correct - one output from the SG4 is at 0 degrees phase angle, going into one channel on the amp, and the other is at 90 degrees going to the other channel on the amp.

See the diagram in post #135

Post in thread '60 WPC Amplifier for DIY Turntable Motor Drive'
https://www.diyaudio.com/community/...diy-turntable-motor-drive.300371/post-5184887

 

[Paulo Batista Gomes]

Thanks @glenv6