Hi everyone,
I have an MGL Odyssey with a UMA hall effect sensor connected to the Mag and a 22k resistor. I'm not sure if there should be a delay in the RPM reading, but it seems like there is about a 4-5 second delay when I push or pull the throttle. Is this normal? Thank you.
MGL Odyssey G2 RPM reading delay
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Re: MGL Odyssey G2 RPM reading delay
From an old post (11/01/2011 08:22) in MGLAvionicsUsers.org forum:
This lag is created in the RDAC itself and is dependent on the number of pulses per RPM.
The more pulses the more "immediate" the RPM indication.
Extra lag however can be introduced if the RPM pulses are not consistent, in other words some get counted, others not. This could be due to a voltage level problem (of the pulse amplitude) or introduced noise. The RDAC will only give out an RPM if it gets a certain number of even spaced pulses (within reason) so it is sure of the RPM. This is part of the whole noise filtering system.
When you kill the engine (rather than run it down slowly to zero RPM) you will see the last measured RPM on the screen for several seconds after the engine has shut down while the RDAC waits for more pulses to come in (perhaps they just dropped due to an iffy signal). Once it times out on this it will then read zero.
Hope this explains it.
Rainier
777drvr wrote:
Hi Guys,
I just completed the installation of an Xtreme/RDAC X combination in my RV-4 . I haven't flown with it yet but did some test runs today . All seemed pretty well except the RPM indication.
I'm using the UMA sensor that screws into the Slick magneto . I have the rpm/rev set to one and found that the best jumper configuration is to have the ballast removed .
My issue is that there seems to be about a 2 second lag in indications . When I start it reads zero for 2 or 3 seconds before anything indicates . Checking the mags also takes longer because I'm waiting for a stable reading . Also on shutdown , the motor is stopped and the RPM's will indicate the last RPM for , you guessed it , 2-3 seconds .
Is this normal life with a digital tach ? If so , I'm not too keen on it .
Any comments or suggestions?
Thanks,
Marc
This lag is created in the RDAC itself and is dependent on the number of pulses per RPM.
The more pulses the more "immediate" the RPM indication.
Extra lag however can be introduced if the RPM pulses are not consistent, in other words some get counted, others not. This could be due to a voltage level problem (of the pulse amplitude) or introduced noise. The RDAC will only give out an RPM if it gets a certain number of even spaced pulses (within reason) so it is sure of the RPM. This is part of the whole noise filtering system.
When you kill the engine (rather than run it down slowly to zero RPM) you will see the last measured RPM on the screen for several seconds after the engine has shut down while the RDAC waits for more pulses to come in (perhaps they just dropped due to an iffy signal). Once it times out on this it will then read zero.
Hope this explains it.
Rainier
777drvr wrote:
Hi Guys,
I just completed the installation of an Xtreme/RDAC X combination in my RV-4 . I haven't flown with it yet but did some test runs today . All seemed pretty well except the RPM indication.
I'm using the UMA sensor that screws into the Slick magneto . I have the rpm/rev set to one and found that the best jumper configuration is to have the ballast removed .
My issue is that there seems to be about a 2 second lag in indications . When I start it reads zero for 2 or 3 seconds before anything indicates . Checking the mags also takes longer because I'm waiting for a stable reading . Also on shutdown , the motor is stopped and the RPM's will indicate the last RPM for , you guessed it , 2-3 seconds .
Is this normal life with a digital tach ? If so , I'm not too keen on it .
Any comments or suggestions?
Thanks,
Marc