Pcmhammer will read but wont write to ecu

[jlvaldez]

Gampy,
The word you're looking for is voltage ripple. AC/DC converters will have a voltage ripple spec (how much the DC voltage wiggles at 60 Hz, or whatever the input frequency is). The ripple gets worse as the load on the supply increases.

The reason is that the DC portion of the AC/DC supply is essentially a giant low pass filter with a large DC capacitor holding charge that gets recharged during the peaks of the AC sinusoidal waveform. The ripple is literally the capacitor getting discharged between the peaks, so as output current increases, you discharge the capacitor more between recharge events and ripple gets worse. This is the main component of noise in a AC/DC supply. To be a real good "clean one" you need a honkin capacitor or a higher frequency input (which isn't really possible for mains supplied things).

Other sources of noise can be noise on the waveforms getting coupled into the DC section of the power stage.

My general recommendation for a "clean" supply is pick up a AC/DC converter (NOT a battery charger, they often have constant current/constant voltage modes depending on the battery they think they're charging), that is rated for your desired output voltage and ~2-5x your anticipated peak output current. Another option is looking at the ripple spec of a supply at a given load and ensuring it is low (generally 1-3% of output supply is considered acceptable for most applications).

[Gampy]

Thank ya sir!
Appreciate it.

Anyway to clean this EVENTEK one up ??

[MudDuck514]

Hi all,

Gampy, the quick and easy way is to load the PSU with a small battery such as one from a UPS.
The better way would be to find a capacitor of at least 100,000 micro Farad, and put it ACROSS the PSU terminals.
The Voltage rating needs to be at LEAST 16v. 20v or 25v being the better choice.

Mike

[Gampy]

The need is variable ... Thus a battery won't get'r done!

It's a 30 volt unit, I'll see if I can find one to cover that ...

Typical Aluminum Electrolytic one ??

Thank you

[MudDuck514]

Hi all,

Gampy, a 50v electrolytic would work for your PSU.
And, yes the big ones are typically aluminum.

Mike