Testing The Diode Board

[Crossrodes]

I have no spark so I decided to test my diode board since I have had it out of the bike.  I understand electrical circuits and diodes (a previous life) so I think I know what I am doing here (or maybe I am losing it).  I used this test procedure:
http://www.frankhams.freeserve.co.uk/testing_the_diode_board.htm

The results I got were the opposite of what is documented in the circuit diagram and write-up.  I used an Ohmeter and decided that if I had current flow through th diode the test light he refers to in the test would light.  When I took my electronics course I was taught that the current flowed against the arrowhead that represents the diode and it flows from negative to positive.  

Is this procedure that is outlined above by frankhams backwards and/or do the Germans represent a circuit diagram (diodes) opposite than we do in North America?  Boy this is confusing.

I believe my diode board is OK because I do have a consistent short circuit when I test in one direction and I have an open circuit when I test in the opposite direction (switching positive and negative connectors on the Ohmeter).

I  would appreciate any feedback from anyone that had followed this procedure.

[ambrose78]

Hi Crossrodes,


 

The results I got were the opposite of what is documented in the circuit diagram and write-up.I used an Ohmeter and decided that if I had current flow through th diode the test light he refers to in the test would light.When I took my electronics course I was taught that the current flowed against the arrowhead that represents the diode and it flows from negative to positive.

I always thought the current went with the direction of the arrowhead and current arriving from the other direction would hit the closed gate so to speak.

here is a handy link to some diode info
http://www.kpsec.freeuk.com/components/diode.htm

about 3 quarters down the page there is a gif showing roughly what is happening in out diode boards - essentially straightening out AC current to DC via one way gates

 

I believe my diode board is OK because I do have a consistent short circuit when I test in one direction and I have an open circuit when I test in the opposite direction (switching positive and negative connectors on the Ohmeter).

Sounds like your board is working. Provided all the diodes only allow electricity to pass in one direction your diodes are effectively doing their job.

P.

[nhmaf]

Your diode board is probably OK - to test it right you really need to use a multimeter with a diode test function, so that you can see the forward voltage drop across each diode, but the likelihood of a marginal diode, not fully failed, is fairly slim.

Electrons "flow" in the opposite direction of what we typically assume to be positive current flow.  So, the electrons go from negative to positive terminals, "against" the direction of the arrow, but the current flow is take to be from positive to negative, in the direction of the arrow of the diode.

Now, to make your mind bend - do you know that it would take a single particular electron several hours to "move" from one end of a 4 foot long cable to the other end under the EMF of your 12V battery?   But, electricity moves alot faster than that...

[Barry]

Now, to make your mind bend - do you know that it would take a single particular electron several hours to "move" from one end of a 4 foot long cable to the other end under the EMF of your 12V battery? But, electricity moves alot faster than that...  

Now that is a can of worms .... but true. Drift velocities are very low indeed and AC is said not to move along the conductor at all. For most practical purposes though, like every time I get an electric shock "electricity transfers it's information" at the order of the speed of light.

[zebedee]

Now, to make your mind bend - do you know that it would take a single particular electron several hours to "move" from one end of a 4 foot long cable to the other end under the EMF of your 12V battery?   But, electricity moves alot faster than that...

The movement of electrons propagates a lot faster than the electrons themselves move.

Think of it like a hydraulic system, if the pipes are rigid and the fluid incompressible, squeezing a little fluid in at one end immediately squeezes a little fluid out the far end without very much actual movement happening. When you grab a handful of brakes the fluid in your brake line doesn't go far at all.

[Darwin_R65]

Now, to make your mind bend - do you know that it would take a single particular electron several hours to "move" from one end of a 4 foot long cable to the other end under the EMF of your 12V battery?   But, electricity moves alot faster than that...

i once touched a an electric fence powered by 12v car battery and I moved 10 feet in 0.2 seconds.

 

John

Am I supposed to be laughing at myself while ii write this?  

.

[Darwin_R65]

Two atoms walk into a bar.
One says to the other "Well bugger me, I've lost an electron"
The other atom says "Are you sure"
The first replies "Yep I'm positive."

 [smiley=ROTFLMAO.gif]

John

[Darwin_R65]

This web page gives a very clear description of testing diodes with a multimeter.

http://www.allaboutcircuits.com/vol_3/chpt_3/2.html

I'll stop my rambling now, just noticed my posts 4(3) in a row, and only one was really helpful.

[Barry]

I'll stop my rambling now, just noticed my posts 4(3) in a row, and only one was really helpful.  

... but the others made us laugh  

love the Atom joke... got a real charge out of it

[Lucky_Lou]

Saw a program a while back (probably discovery) about a Boffin at Manchester University ( Ernest Rutherford) i who was credited with being the first to split the atom and one of the first to explain electron flow he sort described it as "Vibration" they recreated some of his experiments proving the structure of atoms  which though completely over my head i found fascinating.
I know it doesnt help the board testing but i thought i would throw it in.
Lou

[zebedee]

i once touched a an electric fence powered by 12v car battery and I moved 10 feet in 0.2 seconds.

I was working on a cannabis crop many years ago in an Australian summer. The next paddock over was full of cows. We took a break and I leant on the top wire of the fence with both sweaty arms from elbow to wrist. I could hear this slight ticking noise, but I didn't make the connection (so to speak) until I stepped away from the fence and got a belt when I had just one hand on the top wire.

It would seem that about two feet of wire on sweaty forearms is too conductive and the resultant current density in my arms was so low I didn't feel a thing until I lifted my arms off the wire.






Oh, the cannabis thing? It was a government approved experimental crop for fibre production; we were working on a prototype machine to process the stalks.

[Barry]

i once touched a an electric fence powered by 12v car battery and I moved 10 feet in 0.2 seconds.

Electric fences powered by a 12v car battery produce very brief pulses of several thousand volts using a storage capacitor a thyristor switch and a pulse transformer.

What does that sound like... an electronic ignition system.

[montmil]

...Oh, the cannabis thing? It was a government approved experimental crop for fibre production; we were working on a prototype machine to process the stalks.

Not a new idea at all. During WWII, many Texas farmers were paid to plant hemp which was used to make all sizes of lines, sheets and hawsers for the US Navy.

One such farm is now a very popular off-road motorcycle park up along the Red River, about twenty-five miles from my home. Even now, six-foot tall hemp plants grow from seeds eaten and "distributed" by birds. The plants are low quality... I am told.

Party on, dudes and dudettes!   Monte