---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Tue 03/30/21: 3 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 12:30 PM - Re: Forest of Tabs in Multiple Locations (MFleming) 2. 01:01 PM - Re: Forest of Tabs in Multiple Locations (rockitdoc) 3. 08:07 PM - Common ground on LM335 doesn't work but common power does? (rparigoris) ________________________________ Message 1 _____________________________________ Time: 12:30:28 PM PST US Subject: AeroElectric-List: Re: Forest of Tabs in Multiple Locations From: "MFleming" So, would it better if the forest of tabs was not grounded at the sub panel and keep the connecting wire? >From reading your book I thought it is better for all grounds to be tied to a central ground location. -------- Michael Fleming Read this topic online here: http://forums.matronics.com/viewtopic.php?p=501159#501159 ________________________________ Message 2 _____________________________________ Time: 01:01:49 PM PST US Subject: AeroElectric-List: Re: Forest of Tabs in Multiple Locations From: "rockitdoc" nuckolls.bob(at)aeroelect wrote: > At 11:29 AM 3/19/2021, you wrote: > > > > > A fellow RV-7 builder has a B&C forest of tabs located on the pilot side of the firewall with battery ground attaching on the hot side. > > > > They also have a small cluster of tabs on the sub panel. This group of tabs is electrically bonded to the sub panel and has a 14awg wire connecting the sub panel tabs to the firewall tabs. This cluster on the sub panel is for the avionics grounds. > > > > Should the sub panel tabs be isolated from the sub panel or is it OK the way it is? > > The 14AWG jumper adds no value in a metal > airplane. I can be deleted and avionics grounded > at the sub-panel. > > > > Bob . . . > > Un impeachable logic: George Carlin asked, "If black boxes > survive crashes, why don't they make the whole airplane > out of that stuff?" So, given the choice: 1) ground tab forest grounded to airframe locally at ground tab mount, or 2) ground tab forest grounded by wire running to battery ground at firewall, which is more 'desirable'? Either? -------- RV14A Began 7-23-20 Fuse and tail Completed 2-20-21 Wiring in Process Waiting on Wings, Finish, Engine Read this topic online here: http://forums.matronics.com/viewtopic.php?p=501160#501160 ________________________________ Message 3 _____________________________________ Time: 08:07:11 PM PST US Subject: AeroElectric-List: Common ground on LM335 doesn't work but common power does? From: "rparigoris" Hi Group Have some Gremlins visiting at hangar and wondering why they are now playing nice. We have a Ilec SC7 variometer. It has a momentary switch that will measure temperature. The temperature sender is a ST LM335 temperature sender. It I think uses Zener technology. The Ilec provides 3 volts to the sender. The LM335 has 3 leads, power, ground and you can add a trimmer pot. We are just using 2 legs like the factory sender is using. Now for our problem, the factory sender wired direct works perfect. Perhaps 1 or 2 degree changes. We decided we want 6 channels. Purchased a nice ro9tary switch from McMaster good for 2 amps and 30 volts DC. We bread boarded 6 senders with a common ground and switched power. Channels would go bonkers from time to time. It would act like the sender was shorted which would have temp fall way down and it would climb back up, then do it again. We were first using a very precise power supply that we can vary voltage. We went from 12 to 14.5 volts, same problem. We had grounds at power supply. Then we switched grounds to the ground at Ilec. No joy. We tried a battery, no joy. We bypassed the switch completely, no joy, it's not the switch. We had things on a bread board, made soldered connections, no joy? Then we decided to share power and switch grounds. All is well? Anyone have any ideas why switching power to senders and using common ground would give problems but sharing power and switching grounds make things OK? BTW we have a handful of senders, we tried many, when grounds were shared random flakiness. Thx. Ron P. P=Perplexed! 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