Hi Hans
Getting parts tomorrow so I went through posts again. If I want to build schematic on post 151 two or three phase with a 15+/- volt power supply will that work with the amps Ralph and I are using???
If I followed the rest of the posts you came up with circuits on post 179/180/192 to use same power supply to power the op amps. But the one requires you come up with a -12 volt supply.
So maybe for us not to swift on the transistor stuff if you could let us know which ones will work and the ones that do not.
Thanks Again Hans
Tom
Getting parts tomorrow so I went through posts again. If I want to build schematic on post 151 two or three phase with a 15+/- volt power supply will that work with the amps Ralph and I are using???
If I followed the rest of the posts you came up with circuits on post 179/180/192 to use same power supply to power the op amps. But the one requires you come up with a -12 volt supply.
So maybe for us not to swift on the transistor stuff if you could let us know which ones will work and the ones that do not.
Thanks Again Hans
Tom
Hi Tom,
Although Hans refers to +/- 12V in some places and +/-15V in others you can use whichever you choose, they are both equally functional.
I shall use +/-12 because I have a spare small 12V smps available.
I've ordered up several oscillators, both analog and digital, and will see which one gives me the best results
One of them should allow me to generate both Sine and Cosine outputs, which will allow me to use the circuit on #167.
I won't be using 0.1% resistors, I'll try with measured 1% ones, but if need be I may use the nearest metal film 1% below the required value and add a 10+ turn cermet preset to get the exact value.
Ralph
Although Hans refers to +/- 12V in some places and +/-15V in others you can use whichever you choose, they are both equally functional.
I shall use +/-12 because I have a spare small 12V smps available.
I've ordered up several oscillators, both analog and digital, and will see which one gives me the best results
One of them should allow me to generate both Sine and Cosine outputs, which will allow me to use the circuit on #167.
I won't be using 0.1% resistors, I'll try with measured 1% ones, but if need be I may use the nearest metal film 1% below the required value and add a 10+ turn cermet preset to get the exact value.
Ralph
Hi Tom,
Only posting #180 used a separate -12V power supply, but you must forget this version, it was superseded in posting #192 by only using the Main Amp supply.
So in all cases, you only need a power supply for the Main Amps, that one will also supply the phase splitter.
And you can use either #179 or #192.
But I am adding another idea to make #179 even more universal.
You can use it for 3 phases like shown in #179. When switching from 33 1/3 to 45 RPM you will have to change two resistors R3 and R6, with values as mentioned in the circuit diagram.
However when using it for 2 Phase Motors, with the right resistor values for R3 and R6, you can use output Phase_2 for 81Hz and output Phase_3 for 60Hz. So when switching from 33 1/3 to 45 you don't have to switch resistors, all you have to do is to take the other output.
Once adjusted, you will never have to touch the RC networks again.
That makes this circuit very universal in its application, switch nothing with 2 phase motors and switch 2 resistors with 3 phase motors when changing RPM.
See the correct values below for 2 Phase motors for 60Hz and 81Hz.
Hans
Hi Ralph,
If there is any confusion, let me repeat that just one power supply is needed, the one feeding the main amps.
This power supply will also supply the phase splitter.
So whatever has been mentioned about +/-12 or +/- 15 Volt, that can all be scrapped, because the Main amps have AC inputs and don't care about DC from the phase splitter.
That is why I have also inserted schematically one Main Amp in #179, to show that its output is free from DC, despite the fact that the phase splitter has 12V DC on its outputs.
Hans
Hans, If I understand this quote from post 192 that with this circuit I can build a splitter that will handle both a 60hz and 81hz signal from the generator, without switching resistors in the splitter, only downside is 5 op amps instead of three? If so, this is the solution I'd like to take. BTW, I am only interested in the 3 phase version of the splitter.
Another question, are we still talking about using the NE5532 op amps?
Is there a DC offset from the splitter to the amps? The reason I ask is, that I ordered slightly different amps than Ralph (might have been a mistake). The reason I did this is that I thought the volume pot on the amps might be a useful feature. They only have a single ended input, and of course with this cheap Chinese stuff, they never supply a schematic, or documentation of any sort, so don't know if the amps will tolerate a DC offset. I'd be me more than willing to pay an extra dollar or two for documentation, and I'm sure I'm not the only one, but I guess that's too much to ask.
If I do need to block DC, I can just use a cap inline to the amps correct? To find the value of the blocking cap, I assume I can measure the input impedance of the amps, and solve for a decade down from 60hz, which would be 6hz, in order to not get a significant phase shift. (1/(2 x 3.1416 x 6 x z).
I'm interested in trying the ebay signal generator you linked. That .01 hz accuracy would be great. Before I order I think I'll await Tom's post as to his observations on the signal generator angle. This is really an important aspect to my DIY TT project. Thanks again for the work you and others have done on this project.
Hers a link to the amps I ordered:
DC 12V-24V TPA3116 D2 100W Mono Channel Digital Audio Power Amplifier Board car
twystd
Hans, how about this generator? It has 2 phase, exactly what I need for my Hurst motor with 90 Deg shift.
Look at this on eBay:
https://www.ebay.com/itm/351574565789
5MHz 2.4" LCD 2 Channel DDS Function Signal Generator Arbitrary Waveform HG G3F0
I'm boxing everything now. So, the images will be ready soon.
BTW, my current setup with just original Hurst cap gives me 33.8 RPM on TT. Hope that new synthetically made sine waves with 90 Deg diff will give me possibility to fix speed precisely with Hz adjustment.
Sent from my iPhone using Tapatalk
Look at this on eBay:
https://www.ebay.com/itm/351574565789
5MHz 2.4" LCD 2 Channel DDS Function Signal Generator Arbitrary Waveform HG G3F0
I'm boxing everything now. So, the images will be ready soon.
BTW, my current setup with just original Hurst cap gives me 33.8 RPM on TT. Hope that new synthetically made sine waves with 90 Deg diff will give me possibility to fix speed precisely with Hz adjustment.
Sent from my iPhone using Tapatalk
It's just dawned on me, I have the same ebay signal generator that Hans linked, only it's in a case. Here it is:
0.01- 5MHz DDS Function Signal Generator Module Sine/Triangle/Square Wave Sweep
I can just build the splitter, feed it with the generator, and put it into my existing rig to test.
twystd
0.01- 5MHz DDS Function Signal Generator Module Sine/Triangle/Square Wave Sweep
I can just build the splitter, feed it with the generator, and put it into my existing rig to test.
twystd
No, with #192 you have to switch one resistor, use 5 op amps and a a number of 0.1% resistors.
With #179 you have 2 resistors to be switched, use 3 op amps and no precision resistors.
Yes
Yes there is a DC from the splitter, but you can bet that the amp you have ordered also has AC inputs, so don't worry.
These amps are also bridged, very similar to what Ralph has chosen.
What is still to be awaited is how much distortion these switchers produce.
It should be some where between -40dB and -60dB. So it could be that you need some filtering between Amp and Trafo.
But only measuring will give an answer to this question.
Thank you,
Hans
Can the frequency be set in steps of 0.01Hz and can the phase shift between the two channels be set in steps of 1 degree.
And can the frequency be set as low as 60 Hz.
These questions should all be answered with a yes.
And what is the distortion from the sinewave, should it still be filtered to become somewhere between -40dB and -60dB.
In this last case, some extra filtering has to be done without damaging the phase relation.
But in principle, it looks like a very nice device for a 2 phase motor indeed.
Hans
Hans, can you see any reason why the #192 circuit needs 0.1% resistors, but the #179 doesn't.
Is this still the case if #192 is run with a split supply?
Is there any chance of getting a copy of your LTSpice files for further investigation.
Thanks
Ralph
Hey Hans
Was reading through post 179 and noticed you wanted 100 nf ceramic caps on the + side of the 24v supply to the op amp. Do you need to put on the pin or just in series.
Also looked up adder circuit. So if I kind of get this you just put it in so you could check output voltage in one spot. Could you get the information without the circuit by checking each phase individually. Or is that circuit doing something else? My mind is having a hard time seeing what is going on by combining the 3 phases at one node.
Well as always Thanks for your time Hans before this is over we should have several different workable units. This should put us in a position to do some final testing in our equipment and see if we can hear differences. Analogue vs Digital etc...
Thanks Tom
Was reading through post 179 and noticed you wanted 100 nf ceramic caps on the + side of the 24v supply to the op amp. Do you need to put on the pin or just in series.
Also looked up adder circuit. So if I kind of get this you just put it in so you could check output voltage in one spot. Could you get the information without the circuit by checking each phase individually. Or is that circuit doing something else? My mind is having a hard time seeing what is going on by combining the 3 phases at one node.
Well as always Thanks for your time Hans before this is over we should have several different workable units. This should put us in a position to do some final testing in our equipment and see if we can hear differences. Analogue vs Digital etc...
Thanks Tom
Its always a good idea to decouple the pins of an op-amp with a capacitor, 0.1uF is the 'standard' value for AF op-amps.
Combining all three phases of a 3 phase supply via resistors will generate a value of 0.0V at the junction if the phases are perfectly balanced, so its a quick and useful way of checking.
As an aside I'm now using two 75VA 12V supplies in series for the 24V supply for my power amps with the center tied to ground, +/-12V for my op-amp circuits now comes for free.
Combining all three phases of a 3 phase supply via resistors will generate a value of 0.0V at the junction if the phases are perfectly balanced, so its a quick and useful way of checking.
As an aside I'm now using two 75VA 12V supplies in series for the 24V supply for my power amps with the center tied to ground, +/-12V for my op-amp circuits now comes for free.
Hi Ralph,
The reason for 0.1% resistors is quite simple.
To start with, the sine and cosine have to be very accurate in their phase shift of 90 degrees.
Then those two signals have to be added and subtracted.
All errors in this proces are adding up and will have relatively large effects on both the Amplitude and on the Phase of the generated phase signals.
A 3 phase motor will run optimally when the sum of the 3 phases is zero.
With errors, to be measured with the 3 resistors adding the 3 phases, any signal other than zero will act as an extra signal on top of the 3 phases.
It is this extra signal that will cause rumble when being too large.
Trimming will be quite difficult because all factors are interrelated.
That's why you need 0.1% resistors for the adder to start with.
All you have to trim in that case is just the RC combination.
Showing the sensitivity, going with R6 from 10k98 to 11k already let the error signal increase a factor 100, from 1 uV to 100 uV with a 0.7 V Phase signal !!
An error in the phase shifter of #179, will never have an effect on the amplitude since the used phase shifters have a gain of 0 dB, independent of frequency.
And there are only 2 RC combinations to be trimmed to get the error signal to practically zero.
So to conclude, going from 2 RC combinations to only one, has its price.
Hans
View attachment 3phase-1.asc
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OK got parts in and got surface mount 5532 op amps. Quess I will drive 20 miles to the electronic store to get ones I can hard wire.
Also got the udb 1005s dds generator today and there are some things I do not understand. The most important ones are the 6 terminals. Has +/- for TTL out,Ext in, and main out. Got the in figured out but what is TTL vs main out. Which one should we be using???
It also has encoder adjustment and DC off set adjustment. In the dark here and manual on line not much help.
Any help would be great.
Thanks Tom
Also got the udb 1005s dds generator today and there are some things I do not understand. The most important ones are the 6 terminals. Has +/- for TTL out,Ext in, and main out. Got the in figured out but what is TTL vs main out. Which one should we be using???
It also has encoder adjustment and DC off set adjustment. In the dark here and manual on line not much help.
Any help would be great.
Thanks Tom
Hi Tom,
The TTL output is a logic level output that corresponds with whatever frequency you have set, normally 0 or 5V.
The 'Main' output will be either 'sine', 'square', or 'sawtooth', depending on the setting.
EXT allows you to use the unit as a frequency meter, monitoring an external input.
The right-hand pots allow you to change the output level and provide a DC offset if required, the latter is not relevant if the unit will be AC coupled to the phase splitter.
I've got a two phase version of the same unit on its way, hopefully it shouldn't take too long to get here.
Good Luck and let us know how you get on.
Ralph
The TTL output is a logic level output that corresponds with whatever frequency you have set, normally 0 or 5V.
The 'Main' output will be either 'sine', 'square', or 'sawtooth', depending on the setting.
EXT allows you to use the unit as a frequency meter, monitoring an external input.
The right-hand pots allow you to change the output level and provide a DC offset if required, the latter is not relevant if the unit will be AC coupled to the phase splitter.
I've got a two phase version of the same unit on its way, hopefully it shouldn't take too long to get here.
Good Luck and let us know how you get on.
Ralph
Hi Ralph
So I just use main for sine wave and leave the ext and TTL blank. No problem not loading ext and TTL terminals???
Ran into a guy at the electronic store who turn me on to sockets for the op amps and printed strip phenolic boards. Do not have to worry about smoking the op amps
Thanks Ralph
Tom
So I just use main for sine wave and leave the ext and TTL blank. No problem not loading ext and TTL terminals???
Ran into a guy at the electronic store who turn me on to sockets for the op amps and printed strip phenolic boards. Do not have to worry about smoking the op amps
Thanks Ralph
Tom
That's it, the use of sockets for op-amps is always a good idea. Over here, on this side of the pond we call the strip board "veroboard", after the originating manufacturer.
You can buy a tool for cutting the strips but I use a new 1/8" drill bit in a spare chuck. If you're not used to using stripboard do be careful as it's possible to leave whiskers of copper which, if you are unlucky, can let the magic smoke out
The "vbias" should be half of the supply, created by either a capacitor decoupled resistor divider, or an op-amp circuit. Examples of each are shown in lower right corner of #179 and #192.
You can buy a tool for cutting the strips but I use a new 1/8" drill bit in a spare chuck. If you're not used to using stripboard do be careful as it's possible to leave whiskers of copper which, if you are unlucky, can let the magic smoke out
The "vbias" should be half of the supply, created by either a capacitor decoupled resistor divider, or an op-amp circuit. Examples of each are shown in lower right corner of #179 and #192.
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Tom if you are referring to the op amp (U2) in the post 179 schematic (furthest to left of box2) pin 3 (op amp 1 in +) goes to the bias supply. The bias supply schematic is right below the phase outputs to the lower right of box 2. It feeds from the 24V supply, and just divides the voltage by 2 (12V out), decouples, and further filters the 24V supply. vcc+ (pin 8) goes directly to the 24V supply and Vcc- (pin 4) goes to ground. I hope this helps, and I understand what you are asking.
twystd
twystd