stevieturbo

And again for negative side. Add protection where necessary.

tblentrprz

The pull up resistor keeps the ECU control wire high (SSR off) until it is pulled low by ECU to turn on.

Sacrilege

iTrader: (1)

300Hz? Why so low? Most DC motor controls are in deep into the kHz range, well out of human hearing range.

LSswap

I agree that higher KHz range will be quieter, but not all drives are designed to tolerate higher rates.

Switching devices are very efficient when they are on or when they are off. They are not efficient during the time they switch from on to off or vice versa. That's when heat is generated. The more times per second that the device is switched on or off, the more heat is generated and does not have a chance to cool.

The devices that can tolerate high KHz switching rates have special components designed to minimize the amount of time taken to switch and therefore survive higher rates. The crydon device is rated to 2,500hz, and at that frequency, it can't even handle 40A. Motor noise typically goes away at about 20,000hz, so that's not even close.

stevieturbo

Because almost no SSR's can go higher than 1Khz, some cheap units 100Hz would be the limit.

My 60A Crydom I think states 1000Hz max, but the 100A Crydom is 800Hz max.

Someone did like to an SSR before where their specs claimed 25kHz, but when I've never found any others even remotely close, I'd question whether it is correct or not.

stevieturbo

Seems it is only the very low current Crydom SSR's that can handle higher frequencies.


Or for the lower current units

Shownomercy

iTrader: (1)

More importantly, holley maxes out at 1000hz so, thats my hard limit.

Shownomercy

iTrader: (1)

To bump this up, fans have been working great and managed to snag back a output (running a termy x so only 4 i/o)

Gonna take the plunge and attempt to pwm my new to me 4303.

Any suggestions on how to setup the axis? Thinking MAP vs rpm?

LSswap

That's effectively what I do.

Shownomercy

iTrader: (1)

Thanks.

I plan on logging fuel temps, but not sure where to place sensor.

I can easily stash it pre/post pump, or post regulator. I am using a 8an pressure port fitting and sensor does not protrude into the main bore area.

https://www.summitracing.com/parts/f...RoChMgQAvD_BwE

LSswap

Logging fuel pressure is great, also good for engine safety. Logging fuel temps is diminishing returns IMHO.

Let us know how loud the fuel pump gets with the low frequency PWM.

Shownomercy

iTrader: (1)

Yup, already log pressure.

Temp is just to verify that the PWM aspect is needed and or working.