212 replies to this topic

[apfever]

That's funny just thinking about it, like the motors could actually keep up with a 10K frequency and what the slew would look like.  

 

I think you have a typo or some misunderstanding of the unit.  Please clarify as a 10KHz frequency isn't practical that I can think of.

[DAVIDG]

Hello all,

 

I bought a 220v inverter to 115v from Amazone but after instead 60Hz it’s 10KHz.

Is this a problem?

 Yes it is problem , It will not run the motors. That frequency is way to fast for the design of the motor and will most likely cause them to quickly over heat and damage the windings.

 

                   - Dave 

[apfever]

Dave, is there really any transformer inverter that would do 220VAC 60Hz to 120VAC 10KHz?  What application if so?  

 

Such a unit would certainly damage something on a telescope if it is real (unit or scope).

[DAVIDG]

Dave, is there really any transformer inverter that would do 220VAC 60Hz to 120VAC 10KHz?  What application if so?  

 

Such a unit would certainly damage something on a telescope if it is real (unit or scope).

These are inverter that take 12 volt and boost the voltage to 220 VAC but at 10 to 20 Khz. The higher the frequency the smaller the transformer that is needed ( ie cheaper). Most modern day electronics run on DC so the power supply takes the AC, rectifies to DC and drops it down to usually 12 to 5 volts. So these types of electronics don't care what the frequency is. 

   AC synchronous motors are designed to the use the 60 Hz or 50 Hz has the timing standard to set the speed of the motor.  The windings are are sized for the current and heat load for voltage and frequency.  They will run in range of about 50Hz to about 75Hz after that they just chatter and get hot. Running one at 10,000 hz  (ie 10 Khz) is almost like running then DC voltage which would be a dead short and just burn everything up.

    Since the owner of the DX8 looks to live were the voltage standard is 220VAC at 50 hz  and the scope has motors design for 120 VAC at 60 HZ the simplest solution is to get a 220 VAC to 12 Volts DC power supply or 12 volt battery and get a  12 DC to 120 VAC inverter running at 60 Hz .

 

                    - Dave 

[deSitter]

These are inverter that take 12 volt and boost the voltage to 220 VAC but at 10 to 20 Khz. The higher the frequency the smaller the transformer that is needed ( ie cheaper). Most modern day electronics run on DC so the power supply takes the AC, rectifies to DC and drops it down to usually 12 to 5 volts. So these types of electronics don't care what the frequency is. 

   AC synchronous motors are designed to the use the 60 Hz or 50 Hz has the timing standard to set the speed of the motor.  The windings are are sized for the current and heat load for voltage and frequency.  They will run in range of about 50Hz to about 75Hz after that they just chatter and get hot. Running one at 10,000 hz  (ie 10 Khz) is almost like running then DC voltage which would be a dead short and just burn everything up.

    Since the owner of the DX8 looks to live were the voltage standard is 220VAC at 50 hz  and the scope has motors design for 120 VAC at 60 HZ the simplest solution is to get a 220 VAC to 12 Volts DC power supply or 12 volt battery and get a  12 DC to 120 VAC inverter running at 60 Hz .

 

                    - Dave 

As I mentioned, you can get a 220/50 square wave inverter for $20 on Ebay. I made a clock drive for my Sears scopes from a 220/50 motor running from this inverter. Runs perfectly, tracks perfectly. You don't need a sine wave inverter to operate a synchronous motor.

 

-drl

[Goofyboy1]

I measured again. Unloaded 15 hz but when I switched the clock drive on I goed too 1.8KHz 117v. 
 

and no 50hz is too slow for Jupiter 8mm oculair.!

[Goofyboy1]

These are inverter that take 12 volt and boost the voltage to 220 VAC but at 10 to 20 Khz. The higher the frequency the smaller the transformer that is needed ( ie cheaper). Most modern day electronics run on DC so the power supply takes the AC, rectifies to DC and drops it down to usually 12 to 5 volts. So these types of electronics don't care what the frequency is. 

   AC synchronous motors are designed to the use the 60 Hz or 50 Hz has the timing standard to set the speed of the motor.  The windings are are sized for the current and heat load for voltage and frequency.  They will run in range of about 50Hz to about 75Hz after that they just chatter and get hot. Running one at 10,000 hz  (ie 10 Khz) is almost like running then DC voltage which would be a dead short and just burn everything up.

    Since the owner of the DX8 looks to live were the voltage standard is 220VAC at 50 hz  and the scope has motors design for 120 VAC at 60 HZ the simplest solution is to get a 220 VAC to 12 Volts DC power supply or 12 volt battery and get a  12 DC to 120 VAC inverter running at 60 Hz .

 

                    - Dave 

That was the problem off getting it working with the stock hand control 

[DAVIDG]

I measured again. Unloaded 15 hz but when I switched the clock drive on I goed too 1.8KHz 117v. 
 

and no 50hz is too slow for Jupiter 8mm oculair.!

 You have to be more specific on what  unit your measuring and how your measuring it.  I  have no idea what you mean here "  I measured again. Unloaded 15 hz but when I switched the clock drive on I goed too 1.8KHz 117v."

 

      From what I understand you have DX-8 with motors that are designed to run on 120 volts AC at 60 Hz. Is this correct ? If so again your simplest solution is 12 volt DC to 120 volt 60 Hz inverter. You can power the 12 volt inverter either with AC to 12 DC power supply or a 12 volt battery.

 

   As I said before you do not need a variable speed drive corrector. The difference between Solar rate which the telescope is gear for and Sidereal rate in only 4 minutes per day and you'll never see that error doing visual observing. If the image is drifting it is because of  the error in the polar alignment of the mount and not because it is not tracking at exactly Sidereal rate.

 

                - Dave 

[Goofyboy1]

Here are some photos 

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[Goofyboy1]

 You have to be more specific on what  unit your measuring and how your measuring it.  I  have no idea what you mean here "  I measured again. Unloaded 15 hz but when I switched the clock drive on I goed too 1.8KHz 117v."

 

      From what I understand you have DX-8 with motors that are designed to run on 120 volts AC at 60 Hz. Is this correct ? If so again your simplest solution is 12 volt DC to 120 volt 60 Hz inverter. You can power the 12 volt inverter either with AC to 12 DC power supply or a 12 volt battery.

 

   As I said before you do not need a variable speed drive corrector. The difference between Solar rate which the telescope is gear for and Sidereal rate in only 4 minutes per day and you'll never see that error doing visual observing. If the image is drifting it is because of  the error in the polar alignment of the mount and not because it is not tracking at exactly Sidereal rate.

 

                - Dave 

The problem is that the original inverter does work properly on 12Vdc. I have received today new D315 transistors and need rewire it. 

[Goofyboy1]

Dave that was the reason I ask where you connected the lm7805 too get a stable 5v and where and which value resistors are on the d315 transistors

[DAVIDG]

 What unit are you measuring ? The one from Amazon that is design for 10Khz output ?  What are   plugging into it ?   Again you need to be more specific on what you are referring to.

    As for the LM7805 it goes on the circuit board of the hand controller and replaces the Zener diode.  So you remove the Zener. One end of the Zener went to ground and the other is were the voltage that powers the hand controller comes in. The Zener regulators that input voltage to what the value of the Zener was.  

 On the 7805, the input is attached to the voltage coming into the hand controller, ground on the 7805 is attached to ground on the hand controller and +5 output of 7805 then goes the were the Zener was. .

  The hand controller has 4 wires going to it, they  are +voltage of around 8 volts, ground, Phase A and Phase B. Phase A goes to the Base of one the D315, Phase B goes to the  Base of the  other D315. 

 

                       - Dave 

[Goofyboy1]

Yes this is the 115v 60hz inverter from Amazon that was advised. 
 

tomorrow I rebuild the criterion’s inverter with new transistors and only working at 12v input. 

[Goofyboy1]

 What unit are you measuring ? The one from Amazon that is design for 10Khz output ?  What are   plugging into it ?   Again you need to be more specific on what you are referring to.

    As for the LM7805 it goes on the circuit board of the hand controller and replaces the Zener diode.  So you remove the Zener. One end of the Zener went to ground and the other is were the voltage that powers the hand controller comes in. The Zener regulators that input voltage to what the value of the Zener was.  

 On the 7805, the input is attached to the voltage coming into the hand controller, ground on the 7805 is attached to ground on the hand controller and +5 output of 7805 then goes the were the Zener was. .

  The hand controller has 4 wires going to it, they  are +voltage of around 8 volts, ground, Phase A and Phase B. Phase A goes to the Base of one the D315, Phase B goes to the  Base of the  other D315. 

 

                       - Dave 

Thanks. 
 

and no resistor on the D315 side

[DAVIDG]

Yes this is the 115v 60hz inverter from Amazon that was advised. 
 

tomorrow I rebuild the criterion’s inverter with new transistors and only working at 12v input. 

 That unit will not run your telescope and can easily damage the motors.  You want sometime similar to this one. Note it states 120 VAC at 60 HZ

 

https://www.amazon.c...130&sr=8-8&th=1

 

 

                   - Dave 

[Goofyboy1]

When a factory’s specification is 60Hz then it must be 60Hz

[DAVIDG]

Thanks. 
 

and no resistor on the D315 side

   If you mean a current limiting resistor on the emitters of D315 then that is how mine is wired.  Both  emitters are wired together and then to a resistor and  the resistor to ground.  I haven't measured the  value but it is most likely a 10 watt resistor and has value of around 8 ohms to limit the current to 1.5 amps. 

 

               - Dave 

[Goofyboy1]

Thanks Dave ,

 

do you have a resistor between the positive and the hand controller? Like on my photo?

[DAVIDG]

Thanks Dave ,

 

do you have a resistor between the positive and the hand controller? Like on my photo?

 You  have to show the photo again. I do believe there is resistor on the V+  line on the 4 pin plug  along with a capacitor between the V+ and ground on the 4 pin connector for the handcontroller. The purpose is to drop the +12 down to about +8  and the +8 is then was reduced to about +6 with the zener diode. I removed the Zener in my unit and replaced it with LM7805 to provide a more stable voltage to hand controller which provide a more stable frequency..

 

                          - Dave 

[Goofyboy1]

Here a little update. 
 

after new wiring and two new D315 I got the same problem dat the r d315 hot unstable and hot.

the only way too got it work was to put -12V input on the Emmiters by bypassing the 9 Ohm resistor.

with -12V on the resistor side nothing worked. 
 

im thinking too cut the Vin/Vout put that is around 8V on the inverter side and hook directly the l7805cv.

So there will no more then 5V too the hand controller. 

 

What will be the best solution so there will not more then 3A go into the secondary side off the transformer?(-12V / +12V \ -12V) 

 

 

long story short:

is it the best way L7805cv on the inverter side instead the hand controller?

how too reduce max A on the transformer?

how too maximise output Voltage on the inverters output side soo it never can damage the clock drive motors?

[DAVIDG]

 The fact that you replaced the power transistors and you still have the same problem tells me that the problem is the function of the circuit in the had controller.  It needs to produce two square waves that are 180 degrees out of phase and running at approximately 60 Hz. So you  need to look at the two signals going to base of each power transistor  You should see signals  similar to what my unit produces. Changing to LM7805 isn't going to fix the problem   if the signals are not there. The LM7805 is just going to make the unit more stable.

 

                 - Dave 

[Goofyboy1]

Hi Dave and everyone that is following this topic!

 

I have only a simple multimeter that can measure frequency and has not a display like your fancy device!

what I today will do is laying down the inverter, hand controller while the inverter is hooked up too a stable 12V adapter so I can hook up my lab power supply too the “5volt” on the hand controller so I’m sure this is stable on the voltage and power read A side! With my infrared heat meter I can search for heating where maybe something is defects of misbehaving.

 

 

im very pleased with all the help that I’m getting here. 

[deSitter]

Hi Dave and everyone that is following this topic!

 

I have only a simple multimeter that can measure frequency and has not a display like your fancy device!

what I today will do is laying down the inverter, hand controller while the inverter is hooked up too a stable 12V adapter so I can hook up my lab power supply too the “5volt” on the hand controller so I’m sure this is stable on the voltage and power read A side! With my infrared heat meter I can search for heating where maybe something is defects of misbehaving.

 

 

im very pleased with all the help that I’m getting here. 

You can get a functional, if not feature-packed, oscilloscope for less than $50. Cheaper than a good Plossl.

 

https://www.amazon.c.../dp/B0C6XPVLPZ/

 

-drl

[Goofyboy1]

 Next I opened the hand controller. The hand controller uses a flip flop transistor circuit  to make the timing pulses that control the power transistors down in the main box.  When I repaired this unit I removed a zener diode that was used to make a not so great voltage regulator and replaced it with LM7805,+5 voltage regulator which is much more stable. You need a stable voltage to have a stable frequency output. 

   In theory the circuit should be self starting but if it doesn't start up  one of  the power transistor is on all the time and it has  full current through it . It then over heats and burns out. This is most common problems I find with any of these drive correctors

   There are four transistor is the circuit. Two make up the flip/flop part and two that are  provided to supply the  needed current and voltage to fully turn on the power transistor. 

   So I attached my O-scope probes to the output of the  two output transistor. These are located on the left edge of the circuit board and the outer leads closest to the edge of the board are the emitters ie sending the pulse back down to the power transistors.

   The traces showed that both transistors were working and the waveform was around 60 Hz.  I could change  it by adjusting the pot on the hand controller. Also both the Fast and Slow buttons  worked. The Fast button changed the frequency to around 70 Hz and the Slow down to around 50 Hz. So that was all working.

 

      Here is  a  picture of the hand controller,  were the probes were attached  and waveform from each transistor.

Criterion handbox transistor output.jpg

 

 

 - Dave 

Gave,

 

is it possible too post a full picture off the wiring from the hand controller input and where you connected the 7805?

 

I think your wiring in the controller is different then the one I have here. 
sorry for the time consuming and annoying questions….😬🥺🫣

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[Goofyboy1]

I’m looking on saved schematics and I’m wondering why here is the 220nF radial condensator is on the output side and on my inverter on the 12Vdc input side

 

*edit*
 

if these devices where made for 100Vac and not 120Vac now in the USA is it wise too manipulating the 12Vdc input too fixed 10 Vdc like how the input from the hand control is step down from 12 Vdc (12.8/13.8V car battery) —> 40 Ohm resistor (??1/2W??) too roughly 10.8 Vdc?

 

Or is it possible too +12Vdc —> 2200uF capacitor —> 40 Ohm resistor  —> transformer&handcontrol
                                - 12Vdc —> 2200uF capacitor —> Emitters & hand control 

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Edited by Goofyboy1, 26 February 2024 - 05:51 AM.