60 WPC Amplifier for DIY Turntable Motor Drive

[flamethrower1]

Furface, cool to see you are from the badger state too.
i am near Appleton

 

[Pyramid]

I've never been to Road America, but it looks interesting. If I do go, I'll drop you a PM beforehand.

Surprised at the number of Cheddarheads on this thread...we must be doing something right.

 

[FurFace]

Yes please do.

flamethrower I would like to extend my offer to you also. karma I tell ya. I'm a flatlander but definitely enjoy my time up north.

 

[flamethrower1]

Yes please do.

flamethrower I would like to extend my offer to you also. karma I tell ya. I'm a flatlander but definitely enjoy my time up north.

Thanks, appreciated

Greg

 

[TerribleT]

Dual 120 toroid transformer

I received the TDA7492 Class D amp from e-Bay yesterday:

TDA-7492 50WPC Class D Amp

The PCB is 3" x 2.5", about the same size as the SG4. I connected the outputs to an Amgis L01-6362 12V toroid transformer and powered the amp using a GST60A24 24VDC 60W wall adapter. To drive the toroid output to 120VAC no load, you will need to reduce the output of the SG4 to 920mVPP using a pot or a fixed voltage divider of 8.2K and 1.8K resistors.

Hi Pyramid,

Thanks for your knowledge and work. I have a couple of dual 120 vac pri. 12v+12v sec. 100va toroids in my junk box. Can one of these be used as the OPT instead of the 115vac transformer that you specified?
Regards,
David

 

[Pyramid]

Hi Pyramid,

Thanks for your knowledge and work. I have a couple of dual 120 vac pri. 12v+12v sec. 100va toroids in my junk box. Can one of these be used as the OPT instead of the 115vac transformer that you specified?
Regards,
David

I've not tried it with 100W xfmrs; it is a bit overkill, but it should work. Although there may be some differences, it wouldn't hurt to try it. You can always go to the smaller xfmr if it doesn't.

 

[TerribleT]

Thanks for your reply. So, 120vac won't be a problem? I'll give it try as soon as all the other parts arrive. I just hope my use of the 100w opt won't blow anything up. Thanks again.
Regards,
David

 

[cygnus x1]

Powering the SG-4

I read that the SG-4 can't be powered from the MK154 w/o decoupling? How about is own PS (rectifier, filter caps, 12V reg) from a tap off of the secondary of the power transformer? Or just it's own 12V reg after the MK154 filter cap?

 

[Pyramid]

The SG4 has a 5V regulator already on the PCB. The problem is the voltage drops briefly and resets the uP. It's easy to isolate from the MK-154. Add a 1A diode (1N4001 or similar) between the MK154 filter cap and the input to the SG4 (anode to MK154, cathode to SG4) and a 1000uFd cap from the SG4 input to ground.

 

[j45yip]

Hi Pyramid,

Is it possible to tap off the GST60A24-P1J 24Vdc for the 12Vdc supply to the SG4 board via a 7812 regulator instead of having 2 separate AC power adapters?

 

[rif]

Hi Pyramid,

Is it possible to tap off the GST60A24-P1J 24Vdc for the 12Vdc supply to the SG4 board via a 7812 regulator instead of having 2 separate AC power adapters?

I was planning that too, but don't take my word for it. I haven't done the math but a 12V drop does concern me from the little i know.

I was also going to put a few seconds delay circuit between the 7812 circuit and the sg4 to prevent the sg4 from going into the startup loop Pyramid described.

 

[Pyramid]

You could do that, but as rif stated, the 12V drop at 80mA will dissipate ~1W. You will need to heatsink the 7812.

You do not need a delay circuit. The GST60A24 is well regulated and will not drop out unless it is overloaded.

 

[j45yip]

Thanks. I'll give that a try then.

 

[flamethrower1]

So I finally got at this project last night, got my resistors soldered on the SG board.
Go the caps soldered on the rotary encoder board, so far, so good.
I would like to ask if someone could verify that this is the correct IC for the encoder board though.
CD4013BM96G4 Texas Instruments | Integrated Circuits (ICs) | DigiKey
This project is rough on old eyes though.

Thanks, Greg

 

[Pyramid]

That is the correct part. Sorry about the SMT layout, but I wanted to keep the PCB small.

 

[flamethrower1]

Sweet, thanks.
No reason to be sorry, I like a challenge, and it will be a very clean layout no doubt.
Appreciated, thanks again.

 

[flamethrower1]

So apparently I have the Chinese version of the Texas Instruments IC.
It only has a printed bar across the body at one end for a reference for mounting.
Is this the O end?
Sorry to ask what I am sure is a stupid question, tried to find some info on the web first and everything I found, they referenced a dimple or dot.

 

[flamethrower1]

Looks like I have reached a brick wall with this project.
I can not even see what I am soldering with this surface mount stuff let alone if it is soldered correctly.
I even have a magnifying glass and reader glasses
Christ it sucks getting old.

 

[ColinAlex]

Don't feel bad, I use an opti-visor and a dissecting scope. They're a life saver and I think it's worth the effort.

 

[ferret]

Old age

Looks like I have reached a brick wall with this project.
I can not even see what I am soldering with this surface mount stuff let alone if it is soldered correctly.
I even have a magnifying glass and reader glasses
Christ it sucks getting old.

Old age is definitely not for sissies!