mike h wrote:

any of you EE types know of a cheap, 150 PSI or better pressure

transducer?

Looking to make a digital compression tester for less than $1500. So far

we

have turned up a 150 PSI digital tire guage and maybe VDO/Autometer/SPAL

150

PSI pressure sensors, but I'm not sure what sort of response time they

would

have. Only need up to idle speed or so, so 40Hz is the max I can see
needing.

Ideas?

Mike Harrington

Mike search  google.com for pressure transducer.
Also Digikey has them.

Paul Lamar

I went through the first 4 or so pages of google and didn't find anything
within my budget that met the specs. I will check out digikey though -
hadn't thought of them and I even have a bag of parts from them on my desk
:)

FWIW, not sure if interest here or not, but I am building the DIY-wideband
O2 sensor board, and my racing partner is getting the O2 sensor (from a
Civic VX), total parts cost around $250 for a supposedly accurate to .1 AFR
quick response meter. I'll let everyone know how well it works, as were are
going to use it along with a Motec unit to dyno tune a friends 3rd gen RX7.

Mike Harrington

For a compression tester a 1K cycle per second response ought to work fine.
Check with Finn he might have some spares. He has a bunch mounted all over
his engine.

Paul Lamar

I buy mine from www.newark.com. About $20.
I prefer the MPX5xxx series. You feed it 5 volts and get a radiometric (linear)
output to pressure with a known offset.
Motorola has apparently changed their web site so an overview of pressure sensors
is harder to find, but see
http://e-www.motorola.com/webapp/sps/site/prod_summary.jsp?code=MPX5999&nodeId=01M98716

Make sure you get the DP or P types (ported).

Finn

Please share some of that pressure data you are collecting on you engine Finn.

Paul Lamar

 
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