Ersterhernd's NUCiMac G4

[ersterhernd]

I just ordered a handful of the BCX38C units. They'll be here in a couple of days. Thx for the advice...


Ersterhernd

 

[sander201]

hi ersterhernd, I have a question about the pinout. In one of your post you say you'd rather use the 3,3 volt instead of 5 volt. But have you replaced all the 5 volt cables to 3,3 volt? I'm talking about the green inverter wire, the red inverter wire and the 5v dvi pins.

thanks in advantage

 

[ersterhernd]

hi ersterhernd, I have a question about the pinout. In one of your post you say you'd rather use the 3,3 volt instead of 5 volt. But have you replaced all the 5 volt cables to 3,3 volt? I'm talking about the green inverter wire, the red inverter wire and the 5v dvi pins.

thanks in advantage

Hi sander201,

The green inverter wire should have no more than 3.3v put to it, same with the orange wire if you have a dimmer hooked up for brightness control. The green wire appears to carry the variable reference voltage from the dimmer (0.7v to 3.2v depending on the dimmer setting) and the orange carries 3.3v continuously. My green wire is connected to my dimming circuit via a 2.7K ohm and a 68K ohm resistor to divide the voltage down slightly to a maximum of 3.2 Volts. Even if the dimmer output is set to maximum, no more than 3.2V can enter the green wire with this setup. If no dimmer is in place, use 3.3 volts on the green with a 1K Ohm resistor in the line (according to JBerg44), and the orange can be left floating.

The red inverter wire is 5v. You can supply it from either the 5v DVI pin 14 as I have done, or from a molex or picopsu supply.

The three wires that supply power through the grey LCD cable are 3.3v, not 5v.



Ersterhernd

 

[ersterhernd]

Installed the PWM fan controller in the other NUCiMac today. This one was built into it's own separate breadboard to house the Picaxe 08M2 controller. Wiring it in was a snap, it is tucked out of the way in the bottom of the dome, wired to a Noctua 92mm fan. It works flawlessly, cycling between three speeds that are totally dead silent when the machine is running, and uses the same software code as the other iMac.



Ersterhernd

 

[ersterhernd]

Hi Ersterhernd. The Transistor must be able to handle the maximum fan current. See Datasheet. Heat dissipation is no problem with PWM. I've just tried a BXC38C (Darlington, Peak Pulse Current 2A, Continuous Collector Current 800mA), works fine.

Cheers! (Prost)

Hi MacTester, the BCX38C transistors showed up in the mail. I tried one and it worked just fine. I had to re-read the datasheet though, because the emitter and collector are reversed on this model as compared to the BC547B's I was using up until now.

The original 100ma versions are working just fine, I think due to the fact that I'm running the Noctua fans throught the ULNA's, there's a little less current flowing through the transistors than the rated 100ma max.

Either way, they both work in this config.


Cheers!

 

[MacTester57]

Hi Ersterhernd,

Yes, the colletor and emitter pins are reversed on this model. Did you add a flyback diode? Kiwi made this hint and he's right!

Good, that it works! When will you add the temperature sensor? My fan controller is finished now and works fine in the Hemi. Will post the result soon.

MacTester

 

[ersterhernd]

Mactester, I read that post about the flyback diode. Compared to you both, I'm an 'electrical illiterate'.

Can you pls explain what this is and how/where to install it. Also a model number if thats applicable. I have an electrical wholesaler locally here and I'm sure they have it.

The temp sensors are coming from China, so hopefully by Christmas I'll get them!


Thanks!

 

[MacTester57]

Mactester, I read that post about the flyback diode. Compared to you both, I'm an 'electrical illiterate'.

Don't tell such things. You can learn everything!

Can you pls explain what this is and how/where to install it. Also a model number if thats applicable. I have an electrical wholesaler locally here and I'm sure they have it.

See here: http://www.tonymacx86.com/imac-mods/104625-mactester57s-hemimac-g4-7.html#post652033
A "1N4007" Diode is OK.

The temp sensors are coming from China, so hopefully by Christmas I'll get them!

You are optimistic! I've ordered them together with the microcontrollers on www.picaxe.com

MacTester

 

[ersterhernd]

You are optimistic! I've ordered them together with the microcontrollers on www.picaxe.com

Damn, I didn't know picaxe sold them. I just completed an order for more 08M2's a couple of days ago.

I'll grab a handful of those diodes...


Thanks!

 

[MacTester57]

I just completed an order for more 08M2's a couple of days ago.

Can't wait to see, what you will do with them...