Matronics Email Lists :: View topic - Home grown VMS Capacitive fuel probe converter

Matronics Email Lists
Web Forum Interface to the Matronics Email Lists

Get Email Distribution Too! FAQ Search Memberlist Usergroups Register

Profile Log in to check your private messages Log in

Home grown VMS Capacitive fuel probe converter

Matronics Email Lists Forum Index -> AeroElectric-List

View previous topic :: View next topic

Author Message

scott(at)tnstaafl.net
Guest

Posted: Sun Apr 08, 2007 7:01 am Post subject: Home grown VMS Capacitive fuel probe converter

It appears the VMS and EI probes output a 2Khz 5vdc frequency plus or 

minus some freq depending on how much the probe is submerged.  These 

probes have 3 wires, I would assume one of the wires is the output, one 

is a grounded reference. Is the other wire power?  



I have found a single chip Freq-2-Voltage convert that only requires a 

couple additional resistors, caps and diode to convert 0-10Khz freq to a 

0-5 volt output. 



http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1335&dDocName=en010486



Now if I can just find out how to hook up the probes... to get their 

output?  Anybody know?



sounds a lot cheaper than $400 for the princeton converters..



Scott



-- 



-

    Truth : the most deadly weapon ever discovered by humanity. Capable of destroying entire perceptual sets, cultures, and realities. Outlawed by all governments everywhere. Possession is normally punishable by death.



    Richard Childers

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

scott(at)tnstaafl.net
Guest

Posted: Sun Apr 08, 2007 3:19 pm Post subject: Home grown VMS Capacitive fuel probe converter

I just found out from the BMA forum archives:



"QUOTE"

Indeed, the Probes are a resistance/capacitance circuit that yields a 

frequency that varies with the fuel changing the capacitance. When the 

probe is hooked to the computer the red is +5v, the black is ground and 

the white is the square wave frequency output back to the computer. When 

you calibrate your tanks, you will supply frequencies to VM and they 

will program the ROM that converts frequencies to gallons.

"UNQUOTE"



So a 5 volt supply is needed to provide voltage to the probes on the red 

wire and the 5vdc square wave freq is produced on the white wire... 

Freq  apx 4Khz empty and 2Khz full.



I'll need to drag my scope down to the hanger to verify this. 



I wonder if a current limiter is built into the probe?



Scott



Scott Derrick wrote:

 	  Quote: 	
		   

 <scott(at)tnstaafl.net>



 It appears the VMS and EI probes output a 2Khz 5vdc frequency plus or 

 minus some freq depending on how much the probe is submerged.  These 

 probes have 3 wires, I would assume one of the wires is the output, 

 one is a grounded reference. Is the other wire power? 

 I have found a single chip Freq-2-Voltage convert that only requires a 

 couple additional resistors, caps and diode to convert 0-10Khz freq to 

 a 0-5 volt output.

 http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1335&dDocName=en010486 

 Now if I can just find out how to hook up the probes... to get their 

 output?  Anybody know?



 sounds a lot cheaper than $400 for the princeton converters..



 Scott




	


-- 



-

    The only security of all is in a free press. The force of public opinion cannot be resisted when permitted freely to be expressed. The agitation it produces must be submitted to. It is necessary, to keep the waters pure.



    Thomas Jefferson to Lafayette, 1823. ME 15:491

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

Display posts from previous:

	Matronics Email Lists Forum Index -> AeroElectric-List	All times are GMT - 8 Hours
Page 1 of 1

Jump to:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum