DIY 4 Phase Sinewave Generator for Turntable Motor Drive

Please note that I am handling domestic USA sales of the programmed SG4 chip only.

All inquiries outside the USA should be directed to Ralphcooke. Ralph also sells the Oshpark boards. I currently do not.

Pyramid is the intellectual property owner. All requests for quantities greater than 3 should be directed to him. Once approved, i will invoice.

Please do not do end runs around the PayPal invoice system. The surprising volume of orders presents a number of challenges. Here’s the procedure:

1. PM me.
2. I’ll give you my email.
3. You’ll confirm the number of boards requested AND your PayPal address.
4. I send you an invoice.
5. You pay that invoice.
6. Boards ship the following Monday morning.
7. There may be a lag between shipments from Digi-Key. I was not expecting to ship 21 boards in the first week of doing this. If this happens, i will let you know in advance.
 
Seth, I got my chip in yesterday's mail. Thank you very much for handling distribution for the US. This project couldn't have come along at a better time for me because now my LP12 needs to be "push started". I really feel it is better to be able to take advantage of modern electronic technology than trying to repair the late 1970's or early '80's design of the Valhalla.
Thank you again to Bill for designing this and making it available to us DIYers.


Ken
 
Hi gents,

New to this thread.

First of all, thanks to Bill (Pyramid) for his efforts and for sharing his knowledge. Truly remarkable. And thanks to all who are collaborating. I feel I have learnt a few things reading this thread.

And a good idea also to keep the OP updated with relevant information.

I will PM Ralphfcooke for a chip and a SG4 board.

My idea is to build an SG4 and a Tachometer for a Rega P25, 115VAC Premotec motor.
 
Member
Joined 2006
Paid Member
Hi all,

I've put together my 3 boards from AshPark and one has an issue with the LED display. Along the top of all the segments are not lighting up. I've compared the working and non-working boards and pin 15 on U3 shows no voltage on the faulty display board and on the good board I'm getting a voltage. I had a spare 74HC595 and swapped it in on the faulty board and go the same results. I suppose I could have 2 bad U3 chips but it seems unlikely.

Any suggestions? Oh, I also swapped around the uP and nothing changed.

Thanks
Rick
 
Hi all,

I've put together my 3 boards from AshPark and one has an issue with the LED display. Along the top of all the segments are not lighting up. I've compared the working and non-working boards and pin 15 on U3 shows no voltage on the faulty display board and on the good board I'm getting a voltage. I had a spare 74HC595 and swapped it in on the faulty board and go the same results. I suppose I could have 2 bad U3 chips but it seems unlikely.

Any suggestions? Oh, I also swapped around the uP and nothing changed.

Thanks
Rick

If a single segment is out on all 4 digits, it is not one of the 2N7000 transistors.

The top segment is "A" on the schematic which is controlled by pin 15 on U3. If there is no voltage at pin 15, check for a short to ground; if that is the case, it could be at pin 15 U3, pin 12 of the display, or R10.

Are you remotely mounting the LED using a cable? If so, please recheck the wiring on the cable.
 
Member
Joined 2006
Paid Member
Thanks Pyramid,

The LED is mounted directly to the board.

I buzzed it out and found a short to ground on the bottom layer on the via between R10 and pin 15 on U3. I scraped it clear with a knife and it's working. I assumed it was a part failure and couldn't see past that.
 
For the fun of it, I bought an Arduino 4 digit 7 segment display for 2 bucks.
I proceeded to mod the pcb to adapt to my choice of LED display which is a Common Cathode type. I had earlier connected it with the same ribbon cable but its not secure and can work loose anytime.
The Arduino display is Common anode type and with surface mounted bunch of resistors and transistors which need 5VDC to power up when used with Arduino. I removed everything till bare board, spent the next hour fitting new headers, the new 7 segment, and wiring up correctly to the header pins. Voila!..works perfectly. Now I don't need some custom connector or pcb for the 7 segment display.
My SG4 controller is now housed into a brand new aluminum chassis and a visit to the machine shop to router the front and back panels for the rest of the controls. Its not yet complete.
 

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Just a update: Everything is running smooth with the BLDC motor and the SG-4. Just tested with a platter for my future DIY TD. Hopefully we'll work with zero problems after is finished.
The front painel of the enclosure is a mess. I discovered that I don't have any skills with the drill, especially to make that rectangular "hole" for the display rsrsrs.
Anyway, I wanna thank everybody, especially Pyramid, for the help.
Pics:
Dropbox - IMG_5317.jpg
Dropbox - IMG_5316.jpg
Dropbox - IMG_5315.jpg
Dropbox - IMG_5320.MOV
 
Pyramid, is this board limited to any frequency? I can think of so many ways to use this board.

For instance I would like to try high frequency AC filaments for my DHT amplifiers. Lets say 100kHz AC and the hum would be way above the audible spectrum...and therefore nothing to worry about. That would be the best of both worlds with the dynamics that only AC heating can bring but none of the tricky hum management.