Using an atx power supply

[fuzz1]

Hi
Would an atx power the cheap ones 500 Watts supply be sufficient to supply 12volts to a car ECU for reading and programming?

[sebage]

In general, any ATX source on +12V voltage (YELLOW wire), should keep the consumption of an ECU, but most of the lower quality sources have a single comparator for all output voltages.
This means that, if you have consumption on only one of the output voltages, you will notice that it will start to decrease. This happens because otherwise, the other voltages would start to increase and the comparator does not allow this to happen.
In short, I assume that you should have a consumer of at least 1A on the +5V voltage (RED wires) to be able to draw enough current from the +12V voltage.
There could be another problem, most ECUs need a voltage slightly higher than 12V (12.5 - 13.5), in order to behave properly.

[fuzz1]

Hi
Thanks for your reply. So adding a buck converter to the power supply might do the job.

I will try to get hold of a buck boost converter so that i can fine tune voltages


As for the power consumption i can add a few power resistors in series to the 5 volts line

[sebage]

Yes, it is also possible.
But as a personal opinion, if you are still going to use a buck converter, I would see more elegant, economical and simple, the use of a laptop charger, 19 - 20V at over 3A.
This means that you will have more than 60W available for the buck converter, with an efficiency of 80% of the most inefficient buck converter, you will still have 48W available at the output, so at 12V at least 4A.
The assembly will be even smaller and you will be able to put it in a case and put only the display and the adjustment element on the panel.

[ceecdk]

Yes of course, I'm even using old AT 200W.

[fuzz1]

Hi
Anyone with an oscilloscope who measured the output of those ATX power supply? I want to know the noise that one can expect using those. Would that be acceptable.