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Kiwi's Next Project - iMac G5

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- I would add a 100nF decoupling cap for the Arduino
Done, board is slightly wider now. Question is it necessary since the Arduino module has this cap already? I also added a reset header next to the cap.

- What's the reason for R9?
I think I added just to limit current from the PSU (not that i measured it). Can it be removed?

- Your inverter circuit could deliver more than 3.3V (depending on the inverter input resistance). I'm using a pullup to 3.3V. (see pic, signal inverted in software, no pulldown resistor in schematic)
Have aligned my board to your circuit. Thanks.

- on your B2 PCB layout a trace from the power transistor to the PWM pin of Fan 3 header is missing?
Well spotted, I had Already Fixed it. Thanks

-The fan 1 cable will not be long enough in a 17" model.
Hmm. The only possibility without a major re-design would be to switch the 4 pin fan header to the right side, but as you can see space is limited, and the 4 pin header is much wider. Can you extend your cable, in the 20" model both top fan cables are not long enough. Thoughts ?

- A 3pin connector for a Servo (D0, 5V, GND) could be useful
I am trying to find some room, should fit but would like to fix up some other things first.

- The new chime module is not yet wired. Relay looks good.
Yes my relays arrived today from China, very small.

- could a voltage divider (or pot) for the chime volume adjustment be useful?
Yes, It can fit. I have chosen a 3386P package, second from left in picture on this page. http://www.robotroom.com/Trimpots.html

Any concerns with this part?
What resistance value would be appropriate?
Does it go on the Chime or amp side of the decoupling capacitor C2?

Other Notes:

I moved the driver transistor, protection diode, and resistor (Q10,R2,D6) to the left side of the board, very close to the 5V supply and relay coil. Better location, gives more space in middle of board, and now I have the polarity of the coil correct.

NOTE: The diagrams were removed See here for final diagrams http://www.tonymacx86.com/imac-mods/107859-kiwis-next-project-imac-g5-27.html#post985797
 
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Hi Kiwi

Done, board is slightly wider now. Question is it necessary since the Arduino module has this cap already?

How wide? Note, that the max dimension for a 17" model is 95 x 64mm. The max component height in the top right corner is about 8mm (because of an indention in this area). The cap may not be necessary, but it's better to have one more for safety...

I think I added just to limit current from the PSU (not that i measured it). Can it be removed?

My current PSU control circuit looks like this. No issues. An emitter follower does not need a base resistor. Note, that the resistance between PSU_ON and GND (measured on the PSU) is about 10k. So there will never flow a huge amount of current.
PSU%20control.png


Hmm. The only possibility without a major re-design would be to switch the 4 pin fan header to the right side, but as you can see space is limited, and the 4 pin header is much wider. Can you extend your cable, in the 20" model both top fan cables are not long enough. Thoughts ?

You could switch fan 1 and fan 2 header. Then move the screw to the right corner (see comment above). But to be honest, it's nor really an issue to extend the fan cable.

What resistance value would be appropriate?

50 to 100kOhm. One outer pin comes from the chime module, the middle pin goes to the 100nF cap, the other outer pin to GND. But I would test all that audio stuff on a breadboard first...

Another note: better don't mount the amp on the back side of the, board. The area below the board is required for all the wires (supply, USB etc.).

MacTester
 
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How wide? Note, that the max dimension for a 17" model is 95 x 64mm.
85 x 63mm

The max component height in the top right corner is about 8mm (because of an indention in this area).
I will have to leave it to you to assess if the current design will work. I have very similar components to your prototype board in this area.

My current PSU control circuit looks like this. No issues. An emitter follower does not need a base resistor. Note, that the resistance between PSU_ON and GND (measured on the PSU) is about 10k. So there will never flow a huge amount of current.
Adopted your circuit.

You could switch fan 1 and fan 2 header. Then move the screw to the right corner (see comment above). But to be honest, it's nor really an issue to extend the fan cable.
The reason for the placement of the screw and surrounding void space, is to allow for the micro usb connector coming into the Arduino. They can be quite chunky, so leaving this area free ensures this issue won't arise.

50 to 100kOhm. One outer pin comes from the chime module, the middle pin goes to the 100nF cap, the other outer pin to GND. But I would test all that audio stuff on a breadboard first...
Done

Another note: better don't mount the amp on the back side of the, board. The area below the board is required for all the wires (supply, USB etc.).
In my build I have no cables under the board, so it really comes down to a user preference, either can be supported.

NOTE: The diagrams were removed See here for final diagrams http://www.tonymacx86.com/imac-mods/107859-kiwis-next-project-imac-g5-27.html#post985797
 
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Hi Kiwi

The reason for the placement of the screw and surrounding void space, is to allow for the micro usb connector coming into the Arduino. They can be quite chunky, so leaving this area free ensures this issue won't arise.

Of course you are correct...

I will have to leave it to you to assess if the current design will work. I have very similar components to your prototype board in this area.

I guess it should fit, because the board is 85mm instead of 95 wide .


The data sheet says, that the sound module has volume buttons... I assume, that an NPN transitsor with a pullup to 3.3V will be necessary to trigger the chime (data sheet page 20).

Thanks for adding the servo header. 5V and GND are reversed (5V is the middle pin and should come from +5V instead of 5VSB).

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Quick Update.

Managed to get the sound module to play back a chime tonight. Simplest circuit, next steps are to integrate it with Arduino amplifier and relay.

To that end

50 to 100kOhm. One outer pin comes from the chime module, the middle pin goes to the 100nF cap, the other outer pin to GND. But I would test all that audio stuff on a breadboard first...

What you stated above contradicts Page 20 of the WTD datasheet, which connect the capacitor to the sound board. Anyway I will go with the design in the data sheet for testing.

Secondly the sound board (Pin15) outputs a high (BUSY) when the module is operating, I will attempt to get this to drive the relay. If I use the same signal for he relay and hold it for 5 seconds, then it would keep playing on an indefinite loop, not a problem, but...

I have now removed the ISD1820 from my design.

I have re-routed 5V to the servo header.

Kiwi.
 
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Hi Kiwi

What you stated above contradicts Page 20 of the WTD datasheet, which connect the capacitor to the sound board. Anyway I will go with the design in the data sheet for testing.

Yes, I know. Amplifier inputs are normally wired that way. The data sheet shows an opamp application, which may be different. Just try it on a breadboard.

Secondly the sound board (Pin15) outputs a high (BUSY) when the module is operating, I will attempt to get this to drive the relay.

Sounds like a good idea.

Unfortunately my sound modules and amps did not yet arrive. So I can't test it. :beachball:

I have re-routed 5V to the servo header.

Thanks

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Hi Kiwi,
I'm new to all this conversion and electronics at all, so my question what kind of 1k resistor should I buy?
 
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Hi Kiwi,
I'm new to all this conversion and electronics at all, so my question what kind of 1k resistor should I buy?
The question of course is what circuit you are going to use it in.

Typically I use; 1/4 watt, metal film, 1% resistors. The only caveat is the wattage, i.e. how much power it can handle. Just realise that if you were to take a 1k 1/4 resistor an plug it into a large voltage source say >50 volts it would probably burn out, just like an american heater (110V) plugged into a european (240V) source. </end of warning>

For any normal electronics this isn't an issue. you need to read about ohms law to understand the basics
https://learn.sparkfun.com/tutorials/voltage-current-resistance-and-ohms-law/all

Also Have a read of this.
http://www.electronics-tutorials.ws/resistor/res_1.html

If you are going to do any electronics many components (like resistors) are cheep. The best way to purchase them is in bulk, like this.
http://www.ebay.com.au/itm/1-10M-56...Electrical_Test_Equipment&hash=item2a2fe1a922

Kiwi
 
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Hi Kiwi

I think, that I've just discovered an error on your fan 1 connector. Are pin 1 and 2 interchanged?

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Hi Kiwi

I think, that I've just discovered an error on your fan 1 connector. Are pin 1 and 2 interchanged?

MacTester
yes thanks you did and I will fix. Question: would it be better if connectire was rotated 180 degrees so locking/key part of the connector was towards the inner part of the board. ?
 
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