Robert, Analog and Max,

Thanks... I understand now about the forum not wanting to support non-isolated ckts. I must have in fact missed it in the user agreements.

Like Max mentioned so many discussions here pertaining to TM controls. I think I have most likely look at all the threads here. Never once did I see where someone pointed out that those threads were in violation.

Should I abandon further pursuit of working on my circuit through the forum?
Or, should I insert an isolation transformer in my schematic?
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R
Like Max mentioned so many discussions here pertaining to TM controls. I think I have most likely look at all the threads here.
Should I abandon further pursuit of working on my circuit through the forum?

Not sure if coincidence, but since the new site management, I have seen a marked reduction in Locked posts on any AC violation .
Max.

 

Ok All.

I have added an Isolation transformer to my schematic.
I am working on the changes as suggested by the AnalogKid.
Once I have the changes completed I will post the up-dated schematic.
This should meet the approval of this sites managment.
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Just completed the revised schematic. It is available with this post.

Added isolation transformer.
Made all changes to low voltage section as suggested by Analogkid on 12/12/2016

I do have a question regarding my C2a and C2b.
Do I actually still need the C2b capacitor? Does not make sense to me.
If the changes I made were correctly implemented I will clean up the drawing further and repost.


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C2a is the storage cap for the 12vdc, and the .22 is a de-coupling (high frequencies) capacitor for the circuit.
Max.

 

Max,

Good I got it.

In the original drawing if you'll recall this low voltage section was derived from the schematic of the MC-60 controller. the cap as listed C2 is rated as .22uF 16v. (that's "point" 22 correct? ) I see in my drawing I have it as .22uF Var.
For some reason (my ignorance) I was thinking it was an electrolytic. I'll need to change that label. If I see this correctly it would be a ceramic cap rated .22uF (point 22) @ 16V.

 

On my MC-60 C2 is .047μf, either Mica or Ceramic, the electrolytic C5 is 22μf.
Max.

 

Max.
I don't have a C5 in my drawing.
I don't have a MC-60 to compare.
All I have is the schematic that Tom Rollins created and posted to this forum.
The C5 there is in a completely different section.
Could the two different values for C2 still accomplish the same function?
Here is a portion from Tom's schematic:

 

There were a lot of mistakes in the early reverse-engineered version.
I am slowly trying to come up with an accurate DWG.
C2 is definitely not a electrolytic.
Max.

 

C2 is definitely not a electrolytic.

It makes sense that it is not.
Especially since there is/was not a filter cap on the output of the low voltage ckt.
Tom Rollins schematic did show the cap to be .22uF
And..... the fact that the Analogkid had me insert an electrolytic in parallel with the C2.
Where is that guy today? I was hoping he could comment on the changes I made at his suggestion.
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There were a lot of mistakes in the early reverse-engineered version.
I am slowly trying to come up with an accurate DWG.
C2 is definitely not a electrolytic.
Max.

I found another mistake in my drawing.
It's in the PWM circuit. I copied this from somewhere here on another thread.
In that schematic it calls for two 1N5158 diodes in parallel beneath the 100K pot.
The 1N5158 diodes are way over sized for their purpose here.
Looking at other drawings of 555 based PWM ckts. it looks like the 1N 4148 would be a better choice.

Is this a correct assumption?
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1n4148 will work.
M.

 

D3 and D4 are directly in parallel with the top half of the bridge and serve no function. Delete them.
Connect the left side of R9 to the big + sign.
Delete D9. Connect R9 directly to D10. Delete that GND connection.
Add a 470 uF 25 V cap in parallel with C2. This filters the rectified AC.
Calculate the peak current through zener D10 and compare that to the data sheet.
Calculate the power dissipation in R9. Use a resistor with at least twice that power rating.

AND - this thread violates the terms of service for this site.

ak

 

Hey Kid....

I made the changes to my schematic as you suggested.
I think I understood you correctly.

Can I get you to take another look of the revised drawing and let me know if I was correct and if there need sto be any further changes.

Thanks

 

You still have a GND to the right of R9. Other than that, it looks good enough to try. The rule of thumb for long term reliability, especially for semiconductors, is never run then at more than 50% of their ratings.
12 Vdc circuit > 25 V capacitors
165 V peak AC out of a bridge > 400 V MOSFET and capacitors
etc.

It affects cost, sometimes size, and often other ratings like a larger Rdson, which affects power dissipation, which affects heatsink size... The 200 V parts will work, and lord knows consumer gear is full of them. But not in my F-15.

ak

 

Latest Revision Of Proposed Power Supply & Speed Control For DC Motor

Thanks to the Analogkid I have the latest revised (corrected) schematic.

I'm ready to breadboard this together and test it out.

 

Keep in mind that your 12vdc common will be referenced to one side of the AC supply and (if you Were to use AC mains Direct.) the common would be referenced to earth ground so keep H.S.'s isolated and it is usually common to use a nylon shaft potentiometer, especially if using a metal knob for the pot.
Earth ground the control enclosure, if metallic.
Max.

 

Keep in mind that your 12vdc common will be referenced to one side of the AC supply and (if you Were to use AC mains Direct.) the common would be referenced to earth ground so keep H.S.'s isolated and it is usually common to use a nylon shaft potentiometer, especially if using a metal knob for the pot.
Earth ground the control enclosure, if metallic.
Max.

Max,

Point noted. Thank You.

Just finished my in house parts search. I have all except the 555.
So, if I can find one locally I will be able to test shortly