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tacho ballast resistor question

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rowlandcarson(at)gmail.co
Guest

Posted: Tue Jan 19, 2021 1:20 am Post subject: tacho ballast resistor question

I’m wiring my Europa XS with a 912ULS engine. I have fitted the factory-supplied UMA tacho and am also taking the engine tacho output to a MGL E-3 engine instrument and a Smart Avionics CSC-1 prop controller.



The UMA manual calls for a 270Ω resistor across the engine tacho output (if the readings are erratic). The MGL manual calls for 220Ω (and one is supplied).



With no electronics shops open nearby in lockdown, it’s going to be awkward buying a single 270Ω resistor. Does anyone know if using the 220Ω resistor I’ve got would make the UMA tacho unhappy? And conversely, would using a 270Ω make the MGL instrument unhappy?



in friendship



Rowland



| Rowland Carson          ... that's Rowland with a 'w' ...

| <rowlandcarson(at)gmail.com>            http://www.rowlandcarson.org.uk

| Skype, Twitter: rowland_carson      Facebook: Rowland Carson

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kingsnjan(at)westnet.com.
Guest

Posted: Tue Jan 19, 2021 2:31 am Post subject: tacho ballast resistor question

Hello Rowland,



If I were you I would get a potentiometer (about 1K) and firstly try it in lieu of a fixed resistor. 



I would be looking for the lowest resistance at which either instrument plays up and similarly the highest reading and then use a fixed resistor of the mid way value. 



BUT THEN ....... We are not in lockdown. 



If I WAS in lockdown, I would try the 220 ohm resistor and see how it goes.  It certainly won’t do any harm. 



Regards



Kingsley in Oz



Sent from my iPhone



 	  Quote: 	
		   On 19 Jan 2021, at 7:29 pm, Rowland Carson <rowlandcarson(at)gmail.com> wrote:

 

 

 

 I’m wiring my Europa XS with a 912ULS engine. I have fitted the factory-supplied UMA tacho and am also taking the engine tacho output to a MGL E-3 engine instrument and a Smart Avionics CSC-1 prop controller.

 

 The UMA manual calls for a 270Ω resistor across the engine tacho output (if the readings are erratic). The MGL manual calls for 220Ω (and one is supplied).

 

 With no electronics shops open nearby in lockdown, it’s going to be awkward buying a single 270Ω resistor. Does anyone know if using the 220Ω resistor I’ve got would make the UMA tacho unhappy? And conversely, would using a 270Ω make the MGL instrument unhappy?

 

 in friendship

 

 Rowland

 

 | Rowland Carson          ... that's Rowland with a 'w' ...

 | <rowlandcarson(at)gmail.com>            http://www.rowlandcarson.org.uk

 | Skype, Twitter: rowland_carson      Facebook: Rowland Carson

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rowlandcarson(at)gmail.co
Guest

Posted: Tue Jan 19, 2021 6:53 am Post subject: tacho ballast resistor question

On 2021-01-19, at 10:24, D McFadyean <ami-mcfadyean(at)talktalk.net> wrote:

 	  Quote: 	
		   Half of the answer is in the instructions!:

 

 "NOTE: If tachometer reads low or is erratic, check engine pick-up sensor. Sensor maybe rusty or

 misaligned, clean and realign as necessary. If the tachometer’s needle pegs when engine is running, install

 a 200 to 680 ohm ½ Watt resistor between the white wire of the tachometer and ground, starting from

 higher resistance.


	




Duncan - thanks for your message, that’s very reassuring. Your instructions must be a different edition, there is no such wording in my UMA manual, just the suggestion I quoted of a 270Ω resistor. I felt it probably wasn’t critical, but wanted to find out if anyone knew better.



in friendship



Rowland



| Rowland Carson          ... that's Rowland with a 'w' ...

| <rowlandcarson(at)gmail.com>            http://www.rowlandcarson.org.uk

| Skype, Twitter: rowland_carson      Facebook: Rowland Carson

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DuaneFamly(at)aol.com
Guest

Posted: Tue Jan 19, 2021 7:45 am Post subject: tacho ballast resistor question

Roland, go ahead and use the resist do you have. There’s  no concern with harming the meter as the resistor is simply dampening the input signal a little bit. The difference between the two will only make a minor difference in your reading. If you have access to an optical tachometer, you can verify your meter reading, as meters do tend to vary a bit. 

Mike Duane N377EA

Europa XS Conventional Gear

Chandler, AZ, USA



Sent from my iPhone



 	  Quote: 	
		   On Jan 19, 2021, at 2:20 AM, Rowland Carson <rowlandcarson(at)gmail.com> wrote:

 

 

 

 I’m wiring my Europa XS with a 912ULS engine. I have fitted the factory-supplied UMA tacho and am also taking the engine tacho output to a MGL E-3 engine instrument and a Smart Avionics CSC-1 prop controller.

 

 The UMA manual calls for a 270Ω resistor across the engine tacho output (if the readings are erratic). The MGL manual calls for 220Ω (and one is supplied).

 

 With no electronics shops open nearby in lockdown, it’s going to be awkward buying a single 270Ω resistor. Does anyone know if using the 220Ω resistor I’ve got would make the UMA tacho unhappy? And conversely, would using a 270Ω make the MGL instrument unhappy?

 

 in friendship

 

 Rowland

 

 | Rowland Carson          ... that's Rowland with a 'w' ...

 | <rowlandcarson(at)gmail.com>            http://www.rowlandcarson.org.uk

 | Skype, Twitter: rowland_carson      Facebook: Rowland Carson

- The Matronics Europa-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?Europa-List

Bill & Sue

Joined: 10 Jan 2006
Posts: 48
Location: Malvern, Worcs. UK (Defford, Croft Farm)

Posted: Wed Jan 20, 2021 1:54 am Post subject: Re: tacho ballast resistor question

Quite so, using the 220Ω resistor will do no harm at all, and I'd be surprised if there was any discernable difference between that and the 270Ω resistor.

 	  DuaneFamly(at)aol.com wrote: 	
		  Roland, go ahead and use the resist do you have. There’s  no concern with harming the meter as the resistor is simply dampening the input signal a little bit. The difference between the two will only make a minor difference in your reading. If you have access to an optical tachometer, you can verify your meter reading, as meters do tend to vary a bit. 

Mike Duane N377EA

Europa XS Conventional Gear

Chandler, AZ, USA



Sent from my iPhone



 	  Quote: 	
		   On Jan 19, 2021, at 2:20 AM, Rowland Carson <rowlandcarson> wrote:

 

 

 

 I’m wiring my Europa XS with a 912ULS engine. I have fitted the factory-supplied UMA tacho and am also taking the engine tacho output to a MGL E-3 engine instrument and a Smart Avionics CSC-1 prop controller.

 

 The UMA manual calls for a 270Ω resistor across the engine tacho output (if the readings are erratic). The MGL manual calls for 220Ω (and one is supplied).

 

 With no electronics shops open nearby in lockdown, it’s going to be awkward buying a single 270Ω resistor. Does anyone know if using the 220Ω resistor I’ve got would make the UMA tacho unhappy? And conversely, would using a 270Ω make the MGL instrument unhappy?

 

 in friendship

 

 Rowland

 

 | Rowland Carson          ... that's Rowland with a 'w' ...

 | <rowlandcarson>            http://www.rowlandcarson.org.uk

 | Skype, Twitter: rowland_carson      Facebook: Rowland Carson

- The Matronics Europa-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?Europa-List

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