Ammeter sensor/shunt

[Bo_Hannington]

I am upgrading my aircraft to D180 with autopilot, I previously have had an early version of Vision Microsystems VM1000, which I am of course removing. However some or the sensors may still be usable. How about the current sensor supplied by Vision. It is a coil through the middle of which a cable carrying the current to be measured passes. The coil is connected to e measurement system. Is this usable on a Dynon?
Bo Hannington

 

[pbennett]

G'day Bo,
I am upgrading XPB from a RMI uMonitor to a D10 and have the same style of current sensor. It's a linear output Hall effect transducer (LOHET). If yours happens to be exactly the make/model that GRT sells, it should work because you should have a config setting for that transducer, as the D10 does. However there are many different LOHET sensitivities and the output is also dependent on the excitation voltage so the odds are against you. I am biting the bullet and using a shunt, despite having to penetrate the firewall.
Peter

 

[jakej]

Bite the bullet BO - you have to change out most, if not all, of the VMS sensors anyway particularly the EGT/CHT as they are the UNgrounded types - the flowscan is useable.

Jake J

 

[dynonsupport]

We can use grounded or ungrounded thermocouples. You shouldn't need to replace the CHT and EGT probes.

 

[jakej]

I stand corrected :-[

Jake J

 

[pbennett]

DS, I plan to fuse the D10 shunt sense wires with polyswitches such as the RXE075 rather than fuses. I am assuming the D10 has sufficiently high input impedance that the polyswitch resistance (<1 ohm) will be irrelevant? You guys are very coy with your interface specs.  [smiley=wink.gif]

Peter

 

[dynonsupport]

The input is a couple k-ohms so you'll be fine. I can get absolute values tomorrow if you need them.

We don't mean to be "coy" with our specs- we'll give out most happily, but the vast majority of our customers don't care how it works, just that it does, so we tend not to go into details in our documentation. Most of our competitors barley have manuals at all!

 

[pbennett]

That's close enough. Thanks

Peter

 

[Bo_Hannington]

Thanks for all the comments guys, all useful & relevant.
Yep, I'll change out the current sensor. It's just that on my other aircraft where I also installed a D180, and used the shunt in the battery circuit so it reads =+e & -ve currents, the measurement is not very good, and drifts around e.g. with engine running & battery charging at a small steady rate, it drifts around & can read anywhere between +5 amps and - 3 amps. I think I might wire the new one in the alternator circuit this time, to measure it's output, rather than the battery load. At least that will be unidirectional.
Bo