---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Mon 02/09/09: 16 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 06:14 AM - Re: Re: Light Speed Ignition with OV (Roger) 2. 06:34 AM - Measuring actual system current (Sam Hoskins) 3. 06:49 AM - Re: Toggle Actuated Circuit Breakers () 4. 06:49 AM - Re: Re: Light Speed Ignition with OV (Robert L. Nuckolls, III) 5. 06:51 AM - Dyno Audio Output () 6. 08:53 AM - Re: Dyno Audio Output (Robert L. Nuckolls, III) 7. 09:11 AM - Re: Measuring actual system current () 8. 10:29 AM - Re: Measuring actual system current (Dale Rogers) 9. 11:27 AM - Re: Dyno Audio Output () 10. 11:45 AM - Re: Dyno Audio Output (Hinde, Frank George (Corvallis)) 11. 01:29 PM - Re: Measuring actual system current () 12. 02:26 PM - Re: Measuring actual system current (jon@finleyweb.net) 13. 02:46 PM - Re: Measuring actual system current (Hinde, Frank George (Corvallis)) 14. 03:54 PM - Re: Measuring actual system current (Sam Hoskins) 15. 05:36 PM - Re: Measuring actual system current (RV Builder (Michael Sausen)) 16. 08:50 PM - Re: Measuring actual system current (Jon Finley) ________________________________ Message 1 _____________________________________ Time: 06:14:33 AM PST US From: "Roger" Subject: Re: AeroElectric-List: Re: Light Speed Ignition with OV > Thanks to Bob and Roger for the informative replies. > > Roger, You mentioned other postings about over-voltage conditions > disabling the Lightspeed ignition. I would like to read about them if you > happen to have a link to the posting. I do not read AeroElectric everyday > and missed the postings. I did read about a Lightspeed ignition that > failed because of overheating. > Thanks, Joe Joe, I have erased most of the recent postings, but here is one in which Bob gives a lot of info: Roger At 11:34 AM 2/4/2009, you wrote: >Bob, > >If I choose the routed suggested by your diagram >to run both ign boxes, would you duplicate the >fuse & 14 AWG from the batt buss or simply run >the 14 AWG to a bus bar such that I could hook up both 5 amp cb's? If you create an ignition bus that services contemporary conventions for minimizing the energy exposure of battery-feed wires during crash events, then you need a disconnect at the battery. A design goal for inoculating the aircraft's accessories from single-points of failure becoming hazardous. This suggests that dual ignition systems are either powered from multiple busses that have low probability of common failure or a single bus with a VERY low probability of failure. We've cited design and maintenance goals for making sure that a battery bus connected to a well maintained RG battery is the single bus with a very low probability of failure. This gave the writer comfort in suggesting that separate fuses for two ignition systems fed from an always hot bus supported was a good design when that bus was supported by (1) well maintained RG battery (2) main alternator (3) aux alternator and (4) protected with very fast fuses that addressed our goals for crash safety. >It appears that this is only adding hardware >from the already existing entry point of the >buss and further extending it to cb's. The only >valid argument I see is the ability to reset a >cb in crisis mode (after a big OV event has >blown both fuses) and continue down the road - >albeit with just about everything else riding on the buss blown as well. That's the real sticking point. If we're doing due diligence and honoring our past teachers, there's no reason for the ignition system to even have such a feature. No mater how honorable the motivation for including it, it created FEMA issues that would get the thing booted from a TC aircraft. > >Thanks so much for your input on this topic. I'm >sorry you are not getting paid for this prime >time activity. Hopefully there is a way we can donate to your cause. I wouldn't do it if it were not useful to me personally . . . so don't be concerned for any overt lack of compensation . . . > Recently I read a thread from some FAA lawyers > who were talking about mechanical standards and > regulation. One said that the FAA regulations > for mechanical compliance (not design) are > designed to be debated. He was referring to the > often vague terms in which the regulations are > written. They should be left open enough for > debate, but not too wide open as to allow broad > deviation from normal practices (depends who's calling what normal). Gee do they think? Do you suppose this is why folks in the airframe services business will shop around for the most compliant ACO to get their STC or 337 on an airplane? Like our tax codes, the FARS are a study in debate prompted by a lack of teaching to simple-ideas. The same phenomenon is infecting industry and government with an MBA/Harvard-Law mentality that curiosity, creativity and wisdom of experience by honorable individuals can be replaced with "The Plan". > >IMO this type of debate should strive to improve >the quality/design of the products offered in >such a way that the improvements are both >advantageous in technological design and add a >factor of safety for the end user. For my $$ >pure technology advancement that adds little or >takes away from the integrity of well known systems is a bad investment. Absolutely. > >So, debate is good and I hope Klaus and others >accept the forward thinking on which their products are offered. Sure. I recall with great fondness the circumstances of my last really rewarding job. I cannot recall a single instance of walking with trepidation into a come-to-jesus meeting in Beech's Targets Division. We had many meetings were some portion of a program was in trouble. As the problem was discussed and ideas circulated around the table, new avenues of attack would emerge. Folks freely volunteered to help out. You always walked out of those meetings with a feeling of accomplishment and renewal. This is how I imagine the meetings in Kelly Johnson's "Skunk Works" worked. This is a tribute to a handful of individuals at the ship's wheel. You can bet the bank on the idea that progress was bench marked by the successful integration of simple-ideas to satisfaction of design goals by a group of honorable individuals. That's my vision of what should happen here on the List. Bob . . . ________________________________ Message 2 _____________________________________ Time: 06:34:30 AM PST US Subject: AeroElectric-List: Measuring actual system current From: Sam Hoskins Is there a way to measure the actual current draw of a system? I finally got my electrically dependent engine started (www.samhoskins.blogspot.com) yesterday and I am using a version of Z-19/RB with a B&C 30A permemant magnet alternator. I have the primary battery installed and a Dynon D180 EFIS/EMS. I would like to be able to determine the real (not estimated) current draw of the system. Once I know that, I will select the appropriate back-up battery, trying to keep it as light as possible. There is an ammeter installed, but I don't think that would help for this data collection. Does anyone have any suggestions how I might go about this? Thanks. Sam Hoskins Murphysboro, IL ________________________________ Message 3 _____________________________________ Time: 06:49:00 AM PST US Subject: RE: AeroElectric-List: Toggle Actuated Circuit Breakers From: Thanks Bob, >>>>>> The big band-aid is to install a separate high current relay to the battery through a LARGE in line fuse . . . probably 30A. Run 14AWG wire from the relay up to the panel mounted 5A breaker. Continue on with what-ever wire is called out to continue on to the ignition system. Now you need switches to control right and left ignition system relays at the battery. See: http://aeroelectric.com/Pictures/Schematics/Battery_Feed_for_Ignition.pd f This approach could be blessed in a TC aircraft as providing circuit protection commensurate with wire sizes AND making the system max-cold when the switches are OFF. Bob . . . <<<<<<<< To eliminate parts count I am planning to use two of the switched circuit breakers to attach my dual plasma III modules. I will plan to run 14 AWG to the breaker/switches. Distance (2.5') and weight are not a factor for two such wires in my setup. In your above sketch are you depicting the two 30A ATC fuse be of the in-line type? What size wire do you suggest between the batt bus and the ATC? Currently I am #10 from the contactor to the batt buss - assume same? Based on the estimated number of life cycles for the P & B switched breakers, I am fine with that risk. Changing them out every 4-5 years would be more than sufficient in my case. Thanks, Glenn From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L. Nuckolls, III Sent: Saturday, February 07, 2009 10:01 AM Subject: Re: AeroElectric-List: Toggle Actuated Circuit Breakers At 07:55 AM 2/5/2009, you wrote: With respect to life cycles how do the switch type circuit breakers hold up? I am looking at the Potter & Brumfield variety. Thanks Go to the Matronics.com archives search and review the 59 or so messages on AeroElectric-List that mention "W31". These are not the best breaker/switch in the world nor are they the worst. Since we're building FAILURE TOLERANT airplanes, use of these devices to meet your design goals is not a decision fraught with evil or risk. Bob . . . ----------------------------------------) ( . . . a long habit of not thinking ) ( a thing wrong, gives it a superficial ) ( appearance of being right . . . ) ( ) ( -Thomas Paine 1776- ) ---------------------------------------- ________________________________ Message 4 _____________________________________ Time: 06:49:48 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Light Speed Ignition with OV At 08:02 AM 2/9/2009, you wrote: > > > >>Thanks to Bob and Roger for the informative replies. >> >>Roger, You mentioned other postings about over-voltage conditions >>disabling the Lightspeed ignition. I would like to read about them >>if you happen to have a link to the posting. I do not read >>AeroElectric everyday and missed the postings. I did read about a >>Lightspeed ignition that failed because of overheating. >>Thanks, Joe > > >Joe, > >I have erased most of the recent postings, but here is one in which >Bob gives a lot of info: > >Roger > AeroElectric-List messages are archived on the matronics.com server. You can search any of the matronics list at: http://www.matronics.com/search/ or review all postings of a particular time frame at: http://www.matronics.com/archives/ Bob . . . ----------------------------------------) ( . . . a long habit of not thinking ) ( a thing wrong, gives it a superficial ) ( appearance of being right . . . ) ( ) ( -Thomas Paine 1776- ) ---------------------------------------- ________________________________ Message 5 _____________________________________ Time: 06:51:10 AM PST US Subject: AeroElectric-List: Dyno Audio Output From: I have a Dynon D100 which provides an audio out feature for alerts, scare tactics etc. I want to take that output and plug it into an input on my GMA-340. Do any of you have an idea to which pin I may attach that output? If you do please specify which side as there is T1 & T2 on the 340. Thanks, Glenn ________________________________ Message 6 _____________________________________ Time: 08:53:51 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Dyno Audio Output At 08:50 AM 2/9/2009, you wrote: >I have a Dynon D100 which provides an audio out feature for alerts, >scare tactics etc. I want to take that output and plug it into an >input on my GMA-340. Do any of you have an idea to which pin I may >attach that output? If you do please specify which side as there is >T1 & T2 on the 340. > >Thanks, >Glenn according to the manual I found at: http://aviation.vortex.is/install/Garmin%20Install%20manuals/GMA-340.pdf Pins 31 and 32 of J1 are an unmuted, unswitched audio input market ALT WRN. These would be suited to warning tone input. The shield ground goes to pin 32. Bob . . . ----------------------------------------) ( . . . a long habit of not thinking ) ( a thing wrong, gives it a superficial ) ( appearance of being right . . . ) ( ) ( -Thomas Paine 1776- ) ---------------------------------------- ________________________________ Message 7 _____________________________________ Time: 09:11:19 AM PST US Subject: RE: AeroElectric-List: Measuring actual system current From: Sam, Great looking aircraft! I've always loved that design. Keep those Vars up. Best of luck. Glenn From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Sam Hoskins Sent: Monday, February 09, 2009 9:32 AM Subject: AeroElectric-List: Measuring actual system current Is there a way to measure the actual current draw of a system? I finally got my electrically dependent engine started (www.samhoskins.blogspot.com) yesterday and I am using a version of Z-19/RB with a B&C 30A permemant magnet alternator. I have the primary battery installed and a Dynon D180 EFIS/EMS. I would like to be able to determine the real (not estimated) current draw of the system. Once I know that, I will select the appropriate back-up battery, trying to keep it as light as possible. There is an ammeter installed, but I don't think that would help for this data collection. Does anyone have any suggestions how I might go about this? Thanks. Sam Hoskins Murphysboro, IL ________________________________ Message 8 _____________________________________ Time: 10:29:18 AM PST US From: Dale Rogers Subject: Re: AeroElectric-List: Measuring actual system current Sam Hoskins wrote: > There is an ammeter installed, but I don't think that would help for > this data collection. Does anyone have any suggestions how I might go > about this? > Umm ... why not? That's what an ammeter does. The are some more sophisticated variations on the theme - load meters. An ammeter can be inserted into any part of the system to measure the current of that branch and its dependent circuits. It sounds like you just need an ammeter with sufficient granularity to measure more than gross changes in current draw. Dale R. COZY MkIV #0497 ________________________________ Message 9 _____________________________________ Time: 11:27:39 AM PST US Subject: RE: AeroElectric-List: Dyno Audio Output From: Excellent, Thanks Bob! I'll give that a go. ................. Do Not Archive -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L. Nuckolls, III Sent: Monday, February 09, 2009 11:52 AM Subject: Re: AeroElectric-List: Dyno Audio Output At 08:50 AM 2/9/2009, you wrote: >I have a Dynon D100 which provides an audio out feature for alerts, >scare tactics etc. I want to take that output and plug it into an >input on my GMA-340. Do any of you have an idea to which pin I may >attach that output? If you do please specify which side as there is >T1 & T2 on the 340. > >Thanks, >Glenn according to the manual I found at: http://aviation.vortex.is/install/Garmin%20Install%20manuals/GMA-340.pdf Pins 31 and 32 of J1 are an unmuted, unswitched audio input market ALT WRN. These would be suited to warning tone input. The shield ground goes to pin 32. Bob . . . ----------------------------------------) ( . . . a long habit of not thinking ) ( a thing wrong, gives it a superficial ) ( appearance of being right . . . ) ( ) ( -Thomas Paine 1776- ) ---------------------------------------- ________________________________ Message 10 ____________________________________ Time: 11:45:22 AM PST US From: "Hinde, Frank George (Corvallis)" Subject: RE: AeroElectric-List: Dyno Audio Output Yes audio tones thru the headset are great way to get your attention..I have a D100 plumbed into my PS7000 audio panel and it has saved my engine at least once. Frank RV7a -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of longg@pjm.com Sent: Monday, February 09, 2009 11:24 AM Subject: RE: AeroElectric-List: Dyno Audio Output Excellent, Thanks Bob! I'll give that a go. ................. Do Not Archive -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L. Nuckolls, III Sent: Monday, February 09, 2009 11:52 AM Subject: Re: AeroElectric-List: Dyno Audio Output At 08:50 AM 2/9/2009, you wrote: >I have a Dynon D100 which provides an audio out feature for alerts, >scare tactics etc. I want to take that output and plug it into an input >on my GMA-340. Do any of you have an idea to which pin I may attach >that output? If you do please specify which side as there is >T1 & T2 on the 340. > >Thanks, >Glenn according to the manual I found at: http://aviation.vortex.is/install/Garmin%20Install%20manuals/GMA-340.pdf Pins 31 and 32 of J1 are an unmuted, unswitched audio input market ALT WRN. These would be suited to warning tone input. The shield ground goes to pin 32. Bob . . . ----------------------------------------) ( . . . a long habit of not thinking ) ( a thing wrong, gives it a superficial ) ( appearance of being right . . . ) ( ) ( -Thomas Paine 1776- ) ---------------------------------------- ________________________________ Message 11 ____________________________________ Time: 01:29:44 PM PST US Subject: RE: AeroElectric-List: Measuring actual system current From: Sam, Just thought of something. Vertical sells that fancy box which claims to measure not only total draw, but the draw on each item at any given time. Unfortunately that's big $$$. I've not seen another system that performs that function independently. From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Sam Hoskins Sent: Monday, February 09, 2009 9:32 AM Subject: AeroElectric-List: Measuring actual system current Is there a way to measure the actual current draw of a system? I finally got my electrically dependent engine started (www.samhoskins.blogspot.com) yesterday and I am using a version of Z-19/RB with a B&C 30A permemant magnet alternator. I have the primary battery installed and a Dynon D180 EFIS/EMS. I would like to be able to determine the real (not estimated) current draw of the system. Once I know that, I will select the appropriate back-up battery, trying to keep it as light as possible. There is an ammeter installed, but I don't think that would help for this data collection. Does anyone have any suggestions how I might go about this? Thanks. Sam Hoskins Murphysboro, IL ________________________________ Message 12 ____________________________________ Time: 02:26:47 PM PST US Subject: RE: AeroElectric-List: Measuring actual system current From: jon@finleyweb.net =0AHi Sam,=0A=0A =0A=0AI'm not an expert here so if somone corrects me, bel ieve them!! ;-)=0A=0A =0A=0AThere are two ways that I know of (probably doz ens of others). If you have a multimeter, some of them will allow you to c heck the draw. I have a cheap unit that states that it can handle 10 amp l oads. You have to break the circuit and run it "thru" the multimeter. Thi s works for the circuits that are easy to get at, not so well for others. Last item on the following page:=0A=0A[http://mechatronics.mech.northwester n.edu/design_ref/tools/multimeter.html] http://mechatronics.mech.northweste rn.edu/design_ref/tools/multimeter.html=0A=0A =0A=0AThe other way is to use of the clamp-on type meters. I don't own one of these but wish I did - sho uld probably splurge on myself one of these days...=0A=0A[http://support.fl uke.com/find-sales/download/asset/2562791_6115_eng_a_w.pdf] http://support. fluke.com/find-sales/download/asset/2562791_6115_eng_a_w.pdf=0A=0A=0AI have no doubt that this is a real cheapo (like everything HF sells) and I do no t KNOW that it will do what we require but I think so:=0A=0A[http://www.har borfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=98675] http://www.harb orfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=98675=0A=0A =0A=0AHth, =0A=0A =0A=0AJon=0A=0A =0A=0A=0A-----Original Message-----=0AFrom: "Sam Hos kins" =0ASent: Monday, February 9, 2009 7:31am=0ATo: "Aerolectric List" =0ASubject: AeroElectr ic-List: Measuring actual system current=0A=0AIs there a way to measure the actual current draw of a system? I finally got my electrically dependent engine started ([http://www.samhoskins.blogspot.com/] www.samhoskins.blogsp ot.com) yesterday and I am using a version of Z-19/RB with a B&C 30A permem ant magnet alternator. I have the primary battery installed and a Dynon D1 80 EFIS/EMS.=0A=0A=0A=0AI would like to be able to determine the real (not estimated) current draw of the system. Once I know that, I will select the appropriate back-up battery, trying to keep it as light as possible.=0A=0A There is an ammeter installed, but I don't think that would help for this d ata collection. Does anyone have any suggestions how I might go about this -======================== ========0A=0A ________________________________ Message 13 ____________________________________ Time: 02:46:57 PM PST US From: "Hinde, Frank George (Corvallis)" Subject: RE: AeroElectric-List: Measuring actual system current Negative, the HF clamp-on unit will NOT work. That unit is for AC (alternat ing current) loads only, not DC (direct current) like our airplanes are bui lt. However the cheapo DC HF multimeter I found to be surprisingly accurate (ca librated it at work) and will measure up to 10A loads and costs $2.99 DO not forget to put the leads back in the correct holes to measure voltage after you measured current though...If you forget and try to measre mains voltage the unit will make a horrendous spark and cease to function...My bo ss did just that checking out his water pump at home, much to my amusement. .:) Frank ________________________________ From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectr ic-list-server@matronics.com] On Behalf Of jon@finleyweb.net Sent: Monday, February 09, 2009 2:24 PM Subject: RE: AeroElectric-List: Measuring actual system current Hi Sam, I'm not an expert here so if somone corrects me, believe them!! ;-) There are two ways that I know of (probably dozens of others). If you have a multimeter, some of them will allow you to check the draw. I have a che ap unit that states that it can handle 10 amp loads. You have to break the circuit and run it "thru" the multimeter. This works for the circuits tha t are easy to get at, not so well for others. Last item on the following p age: http://mechatronics.mech.northwestern.edu/design_ref/tools/multimeter.html The other way is to use of the clamp-on type meters. I don't own one of the se but wish I did - should probably splurge on myself one of these days... http://support.fluke.com/find-sales/download/asset/2562791_6115_eng_a_w.pdf I have no doubt that this is a real cheapo (like everything HF sells) and I do not KNOW that it will do what we require but I think so: http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=98675 Hth, Jon -----Original Message----- From: "Sam Hoskins" Sent: Monday, February 9, 2009 7:31am Subject: AeroElectric-List: Measuring actual system current Is there a way to measure the actual current draw of a system? I finally g ot my electrically dependent engine started (www.samhoskins.blogspot.com) yesterday and I am using a version of Z -19/RB with a B&C 30A permemant magnet alternator. I have the primary batt ery installed and a Dynon D180 EFIS/EMS. I would like to be able to determine the real (not estimated) current draw of the system. Once I know that, I will select the appropriate back-up bat tery, trying to keep it as light as possible. There is an ammeter installed, but I don't think that would help for this d ata collection. Does anyone have any suggestions how I might go about this ? Thanks. Sam Hoskins Murphysboro, IL http://www.matronhttp://www.matronics.com/contribution">http://www.matronic s.com/contributio============= ________________________________ Message 14 ____________________________________ Time: 03:54:15 PM PST US Subject: Re: AeroElectric-List: Measuring actual system current From: Sam Hoskins The reason I can't use the ammeter, I think, is that the readings would be clouded by charging/discharging of the battery. Sam On Mon, Feb 9, 2009 at 12:25 PM, Dale Rogers wrote: > > Sam Hoskins wrote: > >> There is an ammeter installed, but I don't think that would help for this >> data collection. Does anyone have any suggestions how I might go about >> this? >> >> > Umm ... why not? That's what an ammeter does. The are some more > sophisticated variations on the theme - load meters. > An ammeter can be inserted into any part of the system to measure the > current of that branch and its dependent circuits. > It sounds like you just need an ammeter with sufficient granularity to > measure more than gross changes in current draw. > > Dale R. > COZY MkIV #0497 > > ________________________________ Message 15 ____________________________________ Time: 05:36:50 PM PST US From: "RV Builder (Michael Sausen)" Subject: RE: AeroElectric-List: Measuring actual system current Calling it a fancy and expensive box that is used to measure total and indi vidual draw leaves just a tiny bit of the functionality out. :) Michael Do not archive From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectr ic-list-server@matronics.com] On Behalf Of longg@pjm.com Sent: Monday, February 09, 2009 4:27 PM Subject: RE: AeroElectric-List: Measuring actual system current Sam, Just thought of something. Vertical sells that fancy box which claims to me asure not only total draw, but the draw on each item at any given time. Unf ortunately that's big $$$. I've not seen another system that performs that function independently. ________________________________ Message 16 ____________________________________ Time: 08:50:50 PM PST US From: "Jon Finley" Subject: RE: AeroElectric-List: Measuring actual system current Hi Frank, Is it true that NO clamp-on unit will work or are you talking about just the unit that I referenced? Thanks! Jon From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Hinde, Frank George (Corvallis) Sent: Monday, February 09, 2009 3:45 PM Subject: RE: AeroElectric-List: Measuring actual system current Negative, the HF clamp-on unit will NOT work. That unit is for AC (alternating current) loads only, not DC (direct current) like our airplanes are built. However the cheapo DC HF multimeter I found to be surprisingly accurate (calibrated it at work) and will measure up to 10A loads and costs $2.99 DO not forget to put the leads back in the correct holes to measure voltage after you measured current though...If you forget and try to measre mains voltage the unit will make a horrendous spark and cease to function...My boss did just that checking out his water pump at home, much to my amusement..:) Frank _____ From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of jon@finleyweb.net Sent: Monday, February 09, 2009 2:24 PM Subject: RE: AeroElectric-List: Measuring actual system current Hi Sam, I'm not an expert here so if somone corrects me, believe them!! ;-) There are two ways that I know of (probably dozens of others). If you have a multimeter, some of them will allow you to check the draw. I have a cheap unit that states that it can handle 10 amp loads. You have to break the circuit and run it "thru" the multimeter. This works for the circuits that are easy to get at, not so well for others. Last item on the following page: http://mechatronics.mech.northwestern.edu/design_ref/tools/multimeter.html The other way is to use of the clamp-on type meters. I don't own one of these but wish I did - should probably splurge on myself one of these days... http://support.fluke.com/find-sales/download/asset/2562791_6115_eng_a_w.pdf I have no doubt that this is a real cheapo (like everything HF sells) and I do not KNOW that it will do what we require but I think so: http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=98675 Hth, Jon ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-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/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-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.