My new diagnostic routine: invite Emily and Clark over for sundowners and leave my multimeter on the cockpit table. :) Another great video - thanks again!
This was great....Next video should absolutely be a tutorial on common situations where a multimeter can help you identify/troubleshoot a pesky problem.
The first time I got a digital was amazing. Started with test light, resistors and potentiometer. Analog and panel meters, Radio Shack electronics kit. Still like some fine analogs on the boat.
Clark, you are a good, actually very good, teacher. I've used a meter for years but I've never had any formal, or maybe in this case informal, education on the subject. Thank you. I'm looking forward to the rest of the series.
Nice one Clark! Another cool trick with a clamp on amp meter is you can measure really small currents if you loop the wire through the clamp again. This will double the reading. Just divide by two to get the actual value. I do this with my clamp on scope probe.
The Klein Tool CL390 I ordered arrived yesterday & Clark's how-to use it video is hear today. I fiddled around with it a little yesterday, but it's really nice to hear Clark run through the basics & explain everything that I only "sort'a" understand. Btw, Clark, your demos reinforced the recommendation for getting a pair of alligator clips. 😉 Thanks for another great video.
A timely and useful refresher for everyone. Keep up the good work. :-) Just a quick note : Unqualified folk love to say "It's not the volts that kill you, it's the Amps". This is a myth and it's dangerous. 50volts and 10 mA will kill you.
Yes. And we now all know how to calculate the current flow through the body based on the 1.5megaohm reeding I get in this video. But I've never understood why 12v won't conduct enough to feel through 1 inch of flesh when 50v will give you a jolt through 30 inches of flesh. There has to be some threshold effect I assume.
@@EmilyAndClark Might be when the voltage gets high enough to push enough current to cause a shock through the upper layers of relatively high resistance skin at the contact points. The distance between the two contact points then is fairly low resistance in comparison, increasing voltage then solely determines current & shock shock severity. Just writing that makes me shudder. A decrepit but still alive industrial control systems engineer.
@@EmilyAndClark Google this. Conduction of Electrical Current to and Through the Human Body: A Review Raymond M. Fish, PhD, MD, FACEP and Leslie A. Geddes, MS, PhD, DSc Skin resistance might be 200k ohms ie 100k ohms per contact point & the internal muscle & flesh / 'below the skin' path resistance would be 300 ohms regardless of path length, that might be due due to the effective path cross sectional area becoming larger along the length from the contact point to the halfway point. There is also some interesting stuff about the differences between AC & DC current, with AC the current the skin acts as a capacitor insulator so internal current flow can occur without current passing through the skin! 60 cycles would be slightly more problematical than 50 cycles.
It is possible that the Klein clamp-on current measurement was more accurate than the Extech shunt current test. The shunt resistance in these types of meters causes a small voltage drop across the shunt that is used to calculate the current. The voltage drop is called the "burden voltage" and it slightly reduces the current through the circuit under test. This is irrelevant for measurements on a boat, but is a big deal in low level electronics. The Extech manual probably specifies the burden voltage through the meter for low level electronics applications. Current clamps can be impossible to fit in the tight wiring behind a breaker panel and nearby current carrying conductors can affect clamp-on measurements, especially when measuring low currents. If it can fit, clamp-on is king for current measurements above 1A or so IMO. If you use shunt current measurements, be sure to have spare fuses on board. : )
I would just like to add that just to be safe don't wear a watch or rings. When they come into contact and short circuit, it gets very hot very quickly. And once they're burned in, they can't be quickly dislodged.
Thanks again Professor Clark, for demystifying the volt meter and for giving us all good food for thought and great advice to use anywhere. I’ll be avoiding that HF meter 😅 I agree with the ABC gang you and Emily impart a wealth of knowledge and advice that must be shared! Fair Winds
Yes the DC clamp made it worthwhile for me. Before I got one I could only measure up to what my 50 amp shunt meter that had to be hard wired into the system could handle now its hundreds of amps with the clamp. Check out the Ideal brand of meters with dual displays. The second display on the heel of the meter is great when working in awkward locations and makes it very easy to find a position where you'll be able to safely read one of the two displays. Also look for a clamp meter that has a holder for clipping one of the probes to the meter so you won't when using the probes (such as for checking voltage/ohms/frequency/capacitance) need three hands to hold the meter in view, hold the positive probe and then the negative probe. Best
I appreciate these videos. While I am well versed in marine DC electrics, I am an experienced marine mechanic (think pontoons and runabouts), your videos give me a different way of thinking about things I already understand. Your videos expand things for me, can't explain it, but thanks. You're a good teacher, that's a great skill. Are you self taught? Could you share any of the resources you used to gain experience and expertise? Perhaps a good reference book or trade manual? I certainly could not enfineer your bank manager. Your DC battery charging stuff makes sense but how did you educate yourself to be able to figure it all out?
I think my background has a lot to do with my "different way of thinking". I had no education in anything mechanical. My dad is scared of anything that has bolts. I dedicated myself to an understanding of physics, chemistry and software engineering. Got a good grounding in how things work at the low level and problem solving (software is complex problem solving at the most basic level). Once I bought the boat I dove in and figured it all out from first principles. Like my battery knowledge came from the application of chemistry. The only book I can remember reading that helped was "living on 12 volts with ample power". I've recommended it before and it has been found on eBay. So with no rules of thumb shortcuts but getting to the same goal as you where you understand the workings of boats, I have a slightly different "accent" but we both speak the same language.
@@EmilyAndClark My Dad was the opposite of yours having a masters degree in electrical engineering from MIT in 1927. A lot of the things he theorized in his white paper back then took almost half a century to become mainstream in our lives. He would caution us that electricity is like your best friend, just don't treat it with disrespect or take it for granted as even your best friend after you've treated them badly one time to often can turn on you sometimes with disastrous/violent results. Your videos for me take some of the rust off the knife so to speak when the occasional need to trouble shoot a charging system, etc arises. Best
Hi Clark, great videos. Question - no electricity knowledge, what is the resistor for that you hooked up. Why is a resistor used. Is it to draw down the current in a circuit? Your previous video it stressed resistance is detrimental. Thanks for any insight!
@@EmilyAndClark Your previous video focused on proper wiring design. This is important, but knowing how to safely working around voltage is also important. Electricians use non-conducting tools for good reason. Mounting batteries in such a way that nothing can be dropped to create a short is also important.
Or heat up a ring, watchband, bracelet, etc and give you a nasty burn. A metal piece of jewelry burnt to your skin is a miserable thing to deal with. Its really best practice to remove all jewelry when working even with relatively low voltages. Just an old relatively small 9 volt transistor radio battery such as used in many smoke detectors can heat up a key, coin, etc in your pocket and give you a nasty burn or potentially set your clothing to smoldering or to catch on fire. Best
Military flashbacks. Not allowed to wear rings or watches while working with electronics/electrical. We feared getting dinged for that almost as much as facing the enemy.
My new diagnostic routine: invite Emily and Clark over for sundowners and leave my multimeter on the cockpit table. :)
Another great video - thanks again!
Very nice explanation, Clarke. Thanks!
You're welcome. And first comment!
This was great....Next video should absolutely be a tutorial on common situations where a multimeter can help you identify/troubleshoot a pesky problem.
Great idea
The first time I got a digital was amazing. Started with test light, resistors and potentiometer. Analog and panel meters, Radio Shack electronics kit. Still like some fine analogs on the boat.
Yep. Since we can't see electricity. It's like suddenly not being blind
Clark, you are a good, actually very good, teacher. I've used a meter for years but I've never had any formal, or maybe in this case informal, education on the subject. Thank you. I'm looking forward to the rest of the series.
Great post Clark. I'm always learning something new watching here. 🌞🌴⛵️
Nice one Clark! Another cool trick with a clamp on amp meter is you can measure really small currents if you loop the wire through the clamp again. This will double the reading. Just divide by two to get the actual value. I do this with my clamp on scope probe.
Yep. I should have included this. Good point Terry
The Klein Tool CL390 I ordered arrived yesterday & Clark's how-to use it video is hear today. I fiddled around with it a little yesterday, but it's really nice to hear Clark run through the basics & explain everything that I only "sort'a" understand. Btw, Clark, your demos reinforced the recommendation for getting a pair of alligator clips. 😉
Thanks for another great video.
A timely and useful refresher for everyone. Keep up the good work. :-)
Just a quick note : Unqualified folk love to say "It's not the volts that kill you, it's the Amps". This is a myth and it's dangerous. 50volts and 10 mA will kill you.
Yes. And we now all know how to calculate the current flow through the body based on the 1.5megaohm reeding I get in this video.
But I've never understood why 12v won't conduct enough to feel through 1 inch of flesh when 50v will give you a jolt through 30 inches of flesh. There has to be some threshold effect I assume.
@@EmilyAndClark The higher the voltage the more electrons flow, over coming resistance.
@@EmilyAndClark
Might be when the voltage gets high enough
to push enough current to cause a shock through the upper layers of relatively high resistance skin at the contact points. The distance between the two contact points then is fairly low resistance in comparison, increasing voltage then solely determines current & shock shock severity.
Just writing that makes me shudder. A decrepit but still alive industrial control systems engineer.
I think you are on to something.
It's all about the two dead skin layers.
@@EmilyAndClark
Google this.
Conduction of Electrical Current to and Through the Human Body: A Review
Raymond M. Fish, PhD, MD, FACEP and Leslie A. Geddes, MS, PhD, DSc
Skin resistance might be 200k ohms ie 100k ohms per contact point & the internal muscle & flesh / 'below the skin' path resistance would be 300 ohms regardless of path length, that might be due due to the effective path cross sectional area becoming larger along the length from the contact point to the halfway point.
There is also some interesting stuff about the differences between AC & DC current, with AC the current the skin acts as a capacitor insulator so internal current flow can occur without current passing through the skin! 60 cycles would be slightly more problematical than 50 cycles.
It is possible that the Klein clamp-on current measurement was more accurate than the Extech shunt current test. The shunt resistance in these types of meters causes a small voltage drop across the shunt that is used to calculate the current. The voltage drop is called the "burden voltage" and it slightly reduces the current through the circuit under test. This is irrelevant for measurements on a boat, but is a big deal in low level electronics. The Extech manual probably specifies the burden voltage through the meter for low level electronics applications.
Current clamps can be impossible to fit in the tight wiring behind a breaker panel and nearby current carrying conductors can affect clamp-on measurements, especially when measuring low currents. If it can fit, clamp-on is king for current measurements above 1A or so IMO. If you use shunt current measurements, be sure to have spare fuses on board. : )
Good walk through!
Superb. Concise and clear. Just whats needed
I would just like to add that just to be safe don't wear a watch or rings. When they come into contact and short circuit, it gets very hot very quickly. And once they're burned in, they can't be quickly dislodged.
Yes! What he said.
Notice that Emily and I ware woven string rings.
Oops, I missed that! Inattentive, sorry
Thanks again Professor Clark, for demystifying the volt meter and for giving us all good food for thought and great advice to use anywhere. I’ll be avoiding that HF meter 😅 I agree with the ABC gang you and Emily impart a wealth of knowledge and advice that must be shared! Fair Winds
The DC clamp on probe is the only reason I would buy a new meter. The AC clamp on probe did not make it worth while (so I don't have one :)
Yes the DC clamp made it worthwhile for me. Before I got one I could only measure up to what my 50 amp shunt meter that had to be hard wired into the system could handle now its hundreds of amps with the clamp. Check out the Ideal brand of meters with dual displays. The second display on the heel of the meter is great when working in awkward locations and makes it very easy to find a position where you'll be able to safely read one of the two displays. Also look for a clamp meter that has a holder for clipping one of the probes to the meter so you won't when using the probes (such as for checking voltage/ohms/frequency/capacitance) need three hands to hold the meter in view, hold the positive probe and then the negative probe.
Best
I appreciate these videos. While I am well versed in marine DC electrics, I am an experienced marine mechanic (think pontoons and runabouts), your videos give me a different way of thinking about things I already understand. Your videos expand things for me, can't explain it, but thanks. You're a good teacher, that's a great skill.
Are you self taught? Could you share any of the resources you used to gain experience and expertise? Perhaps a good reference book or trade manual?
I certainly could not enfineer your bank manager. Your DC battery charging stuff makes sense but how did you educate yourself to be able to figure it all out?
I think my background has a lot to do with my "different way of thinking".
I had no education in anything mechanical. My dad is scared of anything that has bolts. I dedicated myself to an understanding of physics, chemistry and software engineering. Got a good grounding in how things work at the low level and problem solving (software is complex problem solving at the most basic level). Once I bought the boat I dove in and figured it all out from first principles. Like my battery knowledge came from the application of chemistry. The only book I can remember reading that helped was "living on 12 volts with ample power". I've recommended it before and it has been found on eBay.
So with no rules of thumb shortcuts but getting to the same goal as you where you understand the workings of boats, I have a slightly different "accent" but we both speak the same language.
@@EmilyAndClark My Dad was the opposite of yours having a masters degree in electrical engineering from MIT in 1927. A lot of the things he theorized in his white paper back then took almost half a century to become mainstream in our lives. He would caution us that electricity is like your best friend, just don't treat it with disrespect or take it for granted as even your best friend after you've treated them badly one time to often can turn on you sometimes with disastrous/violent results.
Your videos for me take some of the rust off the knife so to speak when the occasional need to trouble shoot a charging system, etc arises.
Best
🙏🏻...
Hi Clark, great videos. Question - no electricity knowledge, what is the resistor for that you hooked up. Why is a resistor used. Is it to draw down the current in a circuit? Your previous video it stressed resistance is detrimental. Thanks for any insight!
Sometimes you just want to add resistance to a circuit. That's why we have resistors.
Yes, Usually it's to control the current that can flow
@@EmilyAndClark Thanks Clark!!
👍!!!
12V isn't enough to shock an individual, but it's easily enough to start a fire. Try dropping a wrench across the terminals.
Yep.
No one wants fire!
I show that in this video ua-cam.com/video/KsonnEu_H4Q/v-deo.html
@@EmilyAndClark Your previous video focused on proper wiring design. This is important, but knowing how to safely working around voltage is also important. Electricians use non-conducting tools for good reason. Mounting batteries in such a way that nothing can be dropped to create a short is also important.
You are so right
Or heat up a ring, watchband, bracelet, etc and give you a nasty burn. A metal piece of jewelry burnt to your skin is a miserable thing to deal with. Its really best practice to remove all jewelry when working even with relatively low voltages. Just an old relatively small 9 volt transistor radio battery such as used in many smoke detectors can heat up a key, coin, etc in your pocket and give you a nasty burn or potentially set your clothing to smoldering or to catch on fire.
Best
Yes!
Did you notice our wedding rings are made of string. That's why.
You never showed where to put wires when measuring amperage
Read the manual that came with your meter
Military flashbacks. Not allowed to wear rings or watches while working with electronics/electrical. We feared getting dinged for that almost as much as facing the enemy.
Erm "dinged " is you're getting reprimanded.