The frequency counters on most DSOs (including mine) are not very accurate or stable. The SG4 is crystal controlled and the stability is measured in parts per million. Use a dedicated freq counter if in doubt or a stable audio generator with a lissajous pattern on the o-scope and you will see the stability is very good.
I didn’t think it was an issue, I was just curious - Thanks for the explanation! And thanks again for your generosity and time here!
Just a note of thanks to all involved, I put mine together last night and it fired up without a glitch. My TT is still in pieces , so not able to test completely, but frequencies and output voltage looks great. Thank you ..dB
Does anyone else have a pre-programmed chip for the SG4? Curious since it seems Seth Hensel isn't responding currently and I was hoping to get the boards I built up and going.
CDIL in India offer a 3 phase controller for ceiling fans.
https://www.cdil.com/ics/cil5753-three-phase-full-bridge-smart-power-module-bldc-driver
There are other sources too, and here in India there is a big push for these fans, their power consumption at 22 - 28 watts is much less than the 65 watts of the older fans.
Look around, search for 4 phase ceiling fan controller, you should get many hits.
https://www.cdil.com/ics/cil5753-three-phase-full-bridge-smart-power-module-bldc-driver
There are other sources too, and here in India there is a big push for these fans, their power consumption at 22 - 28 watts is much less than the 65 watts of the older fans.
Look around, search for 4 phase ceiling fan controller, you should get many hits.
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Hi Rick, did you manage to find a substitute for the DS 1833 . All the best Rob.
The MCP101-450 is a good substitute for the DS1833. Be sure to order the 'H' suffix:
https://www.diyaudio.com/community/...table-motor-drive.298018/page-53#post-6438818
https://www.diyaudio.com/community/...table-motor-drive.298018/page-53#post-6438818
NareshBrd-
You've posted this several times in this thread and it is off-topic. This thread is about building a DIY controller for existing AC synch TT motors. Maybe you should start a separate thread about using 3 phase ceiling fan motors for TT use. Thanks.
Sorry, I forgot I'd posted earlier.
My thinking was that if something is easily available, why not adapt and use it, instead of developing a brand new system.
What you have done is quite complex, much above the level of the chip I posted about.
There are industrial drives using 3, 4 and 5 phases, maybe if needed you can use a chip from there. If the ones you used in the original design are no longer available.
My thinking was that if something is easily available, why not adapt and use it, instead of developing a brand new system.
What you have done is quite complex, much above the level of the chip I posted about.
There are industrial drives using 3, 4 and 5 phases, maybe if needed you can use a chip from there. If the ones you used in the original design are no longer available.
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Don't get me wrong, I think you have an interesting idea and it is worth exploring further, just not in this thread.
I would be intrigued to see what you come with and how it is implemented.
Those are for brush less DC, (BLDC) motors, currently the latest in my field of plastic molding, also in small machines like refrigerators and inverter air conditioners.
The idea is to save energy by giving just enough energy as the system demands, instead of the on - off cycle.
The overall energy consumption, in BTU / watt has improved only about 5%, in compressors, but the drives are sometimes flimsy, in regard to voltage fluctuations and line noise.
That said, the drive from a small motor, whose speed is controlled by an external input like the fan regulator, or interpreted from the temperature sensor, can be adapted to drive a turn table, which is after all a small motor.
I will not comment on the different deigns for those machines, just that this is now fairly common, the government here is insisting on energy saving devices, and some people are reporting dramatic energy savings.
So gradually becoming mainstream, the ceiling fan which were 65W earlier are now claiming 22W consumption. In our weather, fans are used 9 months or more a year, so the savings add up.
And they evaporate with the repair bill as the fan fails, that is occasional.
The idea is to save energy by giving just enough energy as the system demands, instead of the on - off cycle.
The overall energy consumption, in BTU / watt has improved only about 5%, in compressors, but the drives are sometimes flimsy, in regard to voltage fluctuations and line noise.
That said, the drive from a small motor, whose speed is controlled by an external input like the fan regulator, or interpreted from the temperature sensor, can be adapted to drive a turn table, which is after all a small motor.
I will not comment on the different deigns for those machines, just that this is now fairly common, the government here is insisting on energy saving devices, and some people are reporting dramatic energy savings.
So gradually becoming mainstream, the ceiling fan which were 65W earlier are now claiming 22W consumption. In our weather, fans are used 9 months or more a year, so the savings add up.
And they evaporate with the repair bill as the fan fails, that is occasional.
I now have stock of the latest version of the SG4 chip, this is version 1.05, and allows use of both the PCF-8574A and PCF-8574
versions of the LCD panels. If your display doesn't work correctly adding a jumper between TP1 and the adjacent capacitor should fix the problem.
Many thanks to Bill for continuing to support and update this excellent project!
versions of the LCD panels. If your display doesn't work correctly adding a jumper between TP1 and the adjacent capacitor should fix the problem.
Many thanks to Bill for continuing to support and update this excellent project!
Hi Bill, take a look at the link below, I think he's saying that the run capacitor is increasing the voltage on the capacitor phase. Do you think this is why the creator of the "Norton air power" used a lower voltage transformer for the capacitor phase, so that both voltages end up approximately the same, and also why your SG4 system causes less motor vibration. Interesting stuff.
Don't know about the 'Norton air power', but it might explain why some motor circuits have a resistor in series with the capacitor.
It's not relevant to 2 or 3 phase controllers where separate outputs are created for each motor winding (assuming the windings are the same for each phase)
It's not relevant to 2 or 3 phase controllers where separate outputs are created for each motor winding (assuming the windings are the same for each phase)
When driven from a single phase source, a capacitor is needed to create a phase shift (always less than 90°) in order to approximate the correct phase relationship with the second winding. The second winding is not purely resistive, but also has inductance which will increase the impedance of the winding (Z=R-JXL). The capacitor impedance is +JXc and the reactances will partially cancel leaving a lower total impedance, higher current and higher voltage across the winding, which is an unintended consequence of using a cap to create a phase shift.
Using a 2 phase drive does not require a cap so the impedance of the 2nd winding remains higher and the current and voltage are lower, which should produce lower vibration. The phase is also adjustable and can be exactly 90° (or higher), so it is possible to optimize the drive signal for the winding phase.
Using a 2 phase drive does not require a cap so the impedance of the 2nd winding remains higher and the current and voltage are lower, which should produce lower vibration. The phase is also adjustable and can be exactly 90° (or higher), so it is possible to optimize the drive signal for the winding phase.