---------------------------------------------------------- Kitfox-List Digest Archive --- Total Messages Posted Thu 02/25/10: 4 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 08:03 AM - Re: Hobbs Meter (Mark Napier (napierm)) 2. 08:17 AM - Re: Re: Hobbs Meter (larry huntley) 3. 09:32 AM - Re: Hobbs Meter (akflyer) 4. 11:20 AM - Re: Re: Hobbs Meter (Noel Loveys) ________________________________ Message 1 _____________________________________ Time: 08:03:11 AM PST US Subject: Kitfox-List: Re: Hobbs Meter From: "Mark Napier (napierm)" Skystar sold a kit that mostly solved the problem. It consisted of a wiring diagram and a bridge rectifier. The idea is to connect the two yellow "AC" wires from lighting coil to the "~" inputs on the bridge and then the + and - connections from the bridge to the Hobbs meter. These yellow wires are already connected to the battery regulator so you have to tee off of them. Problem was it didn't work as is. The voltage regulator works by actually shorting the leads from the lighting coil as needed to regulate the charging voltage to the battery. That means under low electrical loads the voltage on the AC pair is usually zero with the occasional 30V spikes. The Hobbs wouldn't run except under a few RPM ranges with stuff turned on in the panel. The answer is to add a capacitor across the Hobbs meter to store up enough charge to run it. I used a 50V 200uF cap and that was plenty. Be sure your Hobbs will run on 5V to 40V. Most of them will. Also note: Don't ground the "-" connection of the Hobbs to the airframe ground. I know is seems wrong but that will interfere with the battery regulator. Just let the circuit float with respect to ground. It works great. Also, whatever wires (either AC or + and -) you have coming through the firewall, be sure to have in-line fuses on them in the engine compartment *before* they go through the metal firewall. Cheers, Mark Napier ---------------------------------------------------------- Time: 06:55:22 AM PST US From: Catz631@AOL.COM Subject: Re: Kitfox-List: Hobbs Meter I had that problem with my Hobbs also. Once in a while I would leave the master on to work on something and forget the Hobbs was running. I solved it by buying a tach that has a power wire that goes to the Hobbs. It applies power only when the engine is running . I believe it was a UMA tach. It sure works nice and problem solved. Dick Maddux Fox 4 912UL Milton,Fl ________________________________ Message 2 _____________________________________ Time: 07:17:21 AM PST US Subject: Kitfox-List: Re: Hobbs Meter From: "Tom Jones" On a two stroke engine you can install a micro switch that gets turned on by the oil pump lever. Make a bracket and place the switch so it gets turned on when the throttle is advanced above idle. -------- Tom Jones Classic IV 503 Rotax, 72 inch Two blade Warp Ellensburg, WA Read this topic online here: http://forums.matronics.com/viewtopic.php?p=287962#287962 ________________________________ Message 2 _____________________________________ Time: 08:17:54 AM PST US From: "larry huntley" Subject: Re: Kitfox-List: Re: Hobbs Meter A friend just picked up a hour meter for his Taylorcraft because the tach was not a recording tach. Runs on a battery and is activated by vibration. Sounds good to me. Larry ________________________________ Message 3 _____________________________________ Time: 09:32:51 AM PST US Subject: Kitfox-List: Re: Hobbs Meter From: "akflyer" you can buy an ac tach that hooks into the yellow power wires coming off the stator. It will only run when the engine is running. http://www.rotaxparts.net/scripts/prodView.asp?idproduct=447 I installed one in mine after I left my master on when I was rebuilding it and racked up about 100 hrs before the battery went dead while I was away at work. -------- DO NOT ARCHIVE Leonard Perry aka SNAKE Soldotna AK Avid "C" / Mk IV 582 (100 hrs and counting on the rebuild) IVO IFA Full Lotus 1450 #1 snake oil salesman since 1-22-2009 I would rather die trying to live, than to live trying not to die.... Read this topic online here: http://forums.matronics.com/viewtopic.php?p=288175#288175 ________________________________ Message 4 _____________________________________ Time: 11:20:09 AM PST US From: "Noel Loveys" Subject: RE: Kitfox-List: Re: Hobbs Meter Get another rectifier regulator and wire it up in parallel with the original rectifier but sent the output leads only to the hobbs and the loading capacitor. That will give you a consistent 13.8V only when the engine is running. I'm sure you will be able to find an automotive rectifier regulator that will be a lot cheaper than the Rotax unit. Noel -----Original Message----- From: owner-kitfox-list-server@matronics.com [mailto:owner-kitfox-list-server@matronics.com] On Behalf Of Mark Napier (napierm) Sent: February 25, 2010 12:33 PM Subject: Kitfox-List: Re: Hobbs Meter Skystar sold a kit that mostly solved the problem. It consisted of a wiring diagram and a bridge rectifier. The idea is to connect the two yellow "AC" wires from lighting coil to the "~" inputs on the bridge and then the + and - connections from the bridge to the Hobbs meter. These yellow wires are already connected to the battery regulator so you have to tee off of them. Problem was it didn't work as is. The voltage regulator works by actually shorting the leads from the lighting coil as needed to regulate the charging voltage to the battery. That means under low electrical loads the voltage on the AC pair is usually zero with the occasional 30V spikes. The Hobbs wouldn't run except under a few RPM ranges with stuff turned on in the panel. The answer is to add a capacitor across the Hobbs meter to store up enough charge to run it. I used a 50V 200uF cap and that was plenty. Be sure your Hobbs will run on 5V to 40V. Most of them will. Also note: Don't ground the "-" connection of the Hobbs to the airframe ground. I know is seems wrong but that will interfere with the battery regulator. Just let the circuit float with respect to ground. It works great. Also, whatever wires (either AC or + and -) you have coming through the firewall, be sure to have in-line fuses on them in the engine compartment *before* they go through the metal firewall. Cheers, Mark Napier ---------------------------------------------------------- Time: 06:55:22 AM PST US From: Catz631@AOL.COM Subject: Re: Kitfox-List: Hobbs Meter I had that problem with my Hobbs also. Once in a while I would leave the master on to work on something and forget the Hobbs was running. I solved it by buying a tach that has a power wire that goes to the Hobbs. It applies power only when the engine is running . I believe it was a UMA tach. It sure works nice and problem solved. Dick Maddux Fox 4 912UL Milton,Fl ________________________________ Message 2 _____________________________________ Time: 07:17:21 AM PST US Subject: Kitfox-List: Re: Hobbs Meter From: "Tom Jones" On a two stroke engine you can install a micro switch that gets turned on by the oil pump lever. Make a bracket and place the switch so it gets turned on when the throttle is advanced above idle. -------- Tom Jones Classic IV 503 Rotax, 72 inch Two blade Warp Ellensburg, WA Read this topic online here: http://forums.matronics.com/viewtopic.php?p=287962#287962 ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message kitfox-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/Kitfox-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/kitfox-list Browse Digests http://www.matronics.com/digest/kitfox-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.