Wiring multiple senders to the same gauge?

pokeybritches · 06-05-2013, 04:45 PM

I'm considering wiring multiple senders to the same gauge, using a rotary selctor switch to determine which sensor's readings are displayed on the gauge. Any reason this is a bad idea? I have a boost, AFR, and oil temp gauge set to go in my 3D Design ash tray pod. I'm due for a transmission and differential fluid flush, so I was considering installing temperature sensors in the drain plugs of each, and then running the wiring to a selector. I'm also considering throwing in a coolant temp sensor.

The reason I'd like the readings is because my cars are daily driven, and I'd like to know when all the fluids are at normal operating temperature prior to me enjoying the car. Overheating isn't really a concern since I don't hit the track like I wish I could. With the vast variations in climate and drive cycles to which the cars are exposed, a standard wait time isn't feasible. Plus, I don't want to wait 15 minutes if I can have fun after only 2

StickMon · 06-05-2013, 05:32 PM

Should work fine. The trick is to find a pretty switch and a nice place/way to mount it.
DigiKey has a selection of 2,515 rotary switches to choose from.
If all of the sensors have a common ground, then you just need a single deck. Otherwise you need 2 decks.
Add more decks and different color LEDs to light your gauge a different color based on what sensor you selected!

pokeybritches · 06-09-2013, 01:03 AM

Quote:

Originally Posted by StickMon

Should work fine. The trick is to find a pretty switch and a nice place/way to mount it.
DigiKey has a selection of 2,515 rotary switches to choose from.
If all of the sensors have a common ground, then you just need a single deck. Otherwise you need 2 decks.
Add more decks and different color LEDs to light your gauge a different color based on what sensor you selected!

This was actually going to be my second question

. I don't want to mount it in a place that sticks out without looking totally OEM, but it would be nice to be able to switch sensors on the fly. Since I won't be using it at the track, I suppose location and easy access aren't critical.

Unfortunately I don't think I'll be able to change the LED lighting the gauge, since I have multiple gauges and don't want a single one sticking out. Good idea though.

I've retrofitted a multifunction M steering wheel, and the buttons don't work with my 2003 car. I could pull it off and do some op testing to see how the buttons work, and maybe design a circuit that utilizes the buttons for sensor selection. If I go this route, I'll need some sort of indicator showing which sensor is selected.

StickMon · 06-09-2013, 02:12 PM

It can be done, but now you're getting into some actual engineering.
Connect a button on the wheel to a binary counter driving an analog multiplexer.
Could put a row of different colored LEDs some place to show which sensor it's reading.
Drive a digital multiplexer from the counter to drive the LEDs.

pokeybritches · 06-09-2013, 04:55 PM

The binary counter is a good idea. I was going to go the microcontroller route since that's what I've worked with before, but I'll check out the binary counter. I know the theory behind a lot of it, but I haven't ordered parts before... other than the Arduino, and I'm not sure that really counts

pokeybritches · 06-09-2013, 04:57 PM

I was thinking of simply going forward to backward WRT the sensors - coolant, oil, transmission, diff. 4 LEDs would suffice, unless I want to get a single LED and program it to blink.

StickMon · 06-10-2013, 12:03 AM

Microcontroller is a pretty good idea. I'm showing my age.
I'm an old school discrete logic guy. My first inclination is always to make everything out of a sack of FETs.

GriffBrew · 06-10-2013, 05:42 AM

Interested to hear about the final decision here. My only concern with the sensors is that the top plugs on diff/tranny may not be submerged (depending on temp and expansion of fluid). But, the bottom ones could allow wire to be ripped out by road debris. What's your plan for mounting sensors?

Walkurie · 06-10-2013, 08:26 AM

Have you considered the P3 gauge? It won't give you trans or diff temps, but everything else you are looking for and then some.
http://www.garthvadarmotorsports.com...-GAUGE-BMW-E85

Relatively easy installation, too. If you still needed the trans and diff info, you can find dedicated instruments and avoid much of the engineering.

pokeybritches · 06-10-2013, 01:33 PM

I had considered it, but I'm looking at $50 in senders/adapters versus $500+ for the vent gauge and additional items.

Shipkiller · 06-10-2013, 05:20 PM

A switch will work but just make sure the switch is a 'Break before Make' switch. If you get a 'Make before Break' switch, then both sensors will be driving the gauge as the contacts are rotated. This is even more important if all the gauges and or sensors are using the same ground line instead of individual grounds.

06-05-2013, 04:45 PM	#1
pokeybritches Colonel 480 Rep 2,782 Posts Drives: ESS/G-Power Z4M, VF Z4, 996tt Join Date: Sep 2009 Location: Los Angeles iTrader: (12) Garage List 2006 BMW Z4M [10.00] 2006 BMW Z4M [8.50] 2003 BMW Z4 3.0i [9.00]	Wiring multiple senders to the same gauge? I'm considering wiring multiple senders to the same gauge, using a rotary selctor switch to determine which sensor's readings are displayed on the gauge. Any reason this is a bad idea? I have a boost, AFR, and oil temp gauge set to go in my 3D Design ash tray pod. I'm due for a transmission and differential fluid flush, so I was considering installing temperature sensors in the drain plugs of each, and then running the wiring to a selector. I'm also considering throwing in a coolant temp sensor. The reason I'd like the readings is because my cars are daily driven, and I'd like to know when all the fluids are at normal operating temperature prior to me enjoying the car. Overheating isn't really a concern since I don't hit the track like I wish I could. With the vast variations in climate and drive cycles to which the cars are exposed, a standard wait time isn't feasible. Plus, I don't want to wait 15 minutes if I can have fun after only 2 __________________ VF Engineering Z4 3.0i, ESS Z4M, G-Power Z4M, 996 Turbo
	Appreciate 0 Tweet Quote

06-05-2013, 05:32 PM	#2
StickMon My other car is on Mars 636 Rep 3,124 Posts Drives: 2006 MR Join Date: Feb 2011 Location: Lo-Cal iTrader: (1)	Should work fine. The trick is to find a pretty switch and a nice place/way to mount it. DigiKey has a selection of 2,515 rotary switches to choose from. If all of the sensors have a common ground, then you just need a single deck. Otherwise you need 2 decks. Add more decks and different color LEDs to light your gauge a different color based on what sensor you selected!
	Appreciate 0 Quote

06-09-2013, 02:12 PM	#4
StickMon My other car is on Mars 636 Rep 3,124 Posts Drives: 2006 MR Join Date: Feb 2011 Location: Lo-Cal iTrader: (1)	It can be done, but now you're getting into some actual engineering. Connect a button on the wheel to a binary counter driving an analog multiplexer. Could put a row of different colored LEDs some place to show which sensor it's reading. Drive a digital multiplexer from the counter to drive the LEDs.
	Appreciate 0 Quote

06-09-2013, 04:55 PM	#5
pokeybritches Colonel 480 Rep 2,782 Posts Drives: ESS/G-Power Z4M, VF Z4, 996tt Join Date: Sep 2009 Location: Los Angeles iTrader: (12) Garage List 2006 BMW Z4M [10.00] 2006 BMW Z4M [8.50] 2003 BMW Z4 3.0i [9.00]	The binary counter is a good idea. I was going to go the microcontroller route since that's what I've worked with before, but I'll check out the binary counter. I know the theory behind a lot of it, but I haven't ordered parts before... other than the Arduino, and I'm not sure that really counts __________________ VF Engineering Z4 3.0i, ESS Z4M, G-Power Z4M, 996 Turbo
	Appreciate 0 Quote

06-09-2013, 04:57 PM	#6
pokeybritches Colonel 480 Rep 2,782 Posts Drives: ESS/G-Power Z4M, VF Z4, 996tt Join Date: Sep 2009 Location: Los Angeles iTrader: (12) Garage List 2006 BMW Z4M [10.00] 2006 BMW Z4M [8.50] 2003 BMW Z4 3.0i [9.00]	I was thinking of simply going forward to backward WRT the sensors - coolant, oil, transmission, diff. 4 LEDs would suffice, unless I want to get a single LED and program it to blink. __________________ VF Engineering Z4 3.0i, ESS Z4M, G-Power Z4M, 996 Turbo
	Appreciate 0 Quote

06-10-2013, 12:03 AM	#7
StickMon My other car is on Mars 636 Rep 3,124 Posts Drives: 2006 MR Join Date: Feb 2011 Location: Lo-Cal iTrader: (1)	Microcontroller is a pretty good idea. I'm showing my age. I'm an old school discrete logic guy. My first inclination is always to make everything out of a sack of FETs.
	Appreciate 0 Quote

06-10-2013, 05:42 AM	#8
GriffBrew Second Lieutenant 5 Rep 234 Posts Drives: 2006 M Roadster Join Date: Jul 2012 Location: Orlando, FL iTrader: (0)	Interested to hear about the final decision here. My only concern with the sensors is that the top plugs on diff/tranny may not be submerged (depending on temp and expansion of fluid). But, the bottom ones could allow wire to be ripped out by road debris. What's your plan for mounting sensors?
	Appreciate 0 Quote

06-10-2013, 08:26 AM	#9
Walkurie Lieutenant 9 Rep 452 Posts Drives: 06 M Roadster / 99 Jaguar XK8 Join Date: Mar 2010 Location: Surf City, CA iTrader: (2)	Wiring multiple senders to the same gauge? Have you considered the P3 gauge? It won't give you trans or diff temps, but everything else you are looking for and then some. http://www.garthvadarmotorsports.com...-GAUGE-BMW-E85 Relatively easy installation, too. If you still needed the trans and diff info, you can find dedicated instruments and avoid much of the engineering. __________________ Vibra Technics engine mounts / Rogue trans mounts / Stoptech brakes / original owner
	Appreciate 0 Quote

06-10-2013, 01:33 PM	#10
pokeybritches Colonel 480 Rep 2,782 Posts Drives: ESS/G-Power Z4M, VF Z4, 996tt Join Date: Sep 2009 Location: Los Angeles iTrader: (12) Garage List 2006 BMW Z4M [10.00] 2006 BMW Z4M [8.50] 2003 BMW Z4 3.0i [9.00]	I had considered it, but I'm looking at $50 in senders/adapters versus $500+ for the vent gauge and additional items. __________________ VF Engineering Z4 3.0i, ESS Z4M, G-Power Z4M, 996 Turbo
	Appreciate 0 Quote

06-10-2013, 05:20 PM	#11
Shipkiller Colonel 188 Rep 2,138 Posts Drives: Me Join Date: Oct 2007 Location: Virginia Beach iTrader: (3) Garage List 2008 BMW Z4M Coupe [8.50] 2003 BMW Z4 Roadster [8.33]	A switch will work but just make sure the switch is a 'Break before Make' switch. If you get a 'Make before Break' switch, then both sensors will be driving the gauge as the contacts are rotated. This is even more important if all the gauges and or sensors are using the same ground line instead of individual grounds.
	Appreciate 0 Quote