DRIVER SCREW UP EL HELP-O PLEASE-O

[amkdeath]

what be wrond wit driver?::

When DMM in series with motor load reads: 187 or so mA MAX (this is as high as I can go)
When DMM in parallel with load reads: 250 or so mA, can go to about an amp
when DMM attatched directly to leads from driver: Exactly like when parallel with load

When cricuit output leads are attached with a 10 ohm ressitor in parallel with DMM I read .2 volts

What is going on!!?!?!?

regards,

amk

 

[amkdeath]

UPDATE READ IMPORTANT

when hooked up win parallel WITH LOAD: 250mA or so

when hooked up directly to dmm: 325 ma
When hooked up in series with resistor: same as with directly hooked up to DMM just slightly different

 

[LarryQ]

Whiskey ..Tango...Foxtrot.......

Slow down......

Have no idea what you are saying.....

Describe the circuit being used........

Motor...what motor belongs in a LD circuit???

LarryQ

 

[chimo]

It's time for you to read up on the effects of inserting the measuring device on the circuit you are trying to measure. When you insert the ammeter in the circuit, it becomes part of the circuit. Also read up on how a probe-type DMM measures current and you will discover why it affects the circuit.

There's a big difference in effects on the circuit between using the 10A scale and the mA scale.

 

[amkdeath]

Whiskey ..Tango...Foxtrot.......

Slow down......

Have no idea what you are saying.....

Describe the circuit being used........

Motor...what motor belongs in a LD circuit???

LarryQ

motor is load, dont have LD yet. DDL circuit

I hooked up my new DMM to my already working laser, and kaboom, i killed it. wooo hoo. :'( :'( :'( :'( :'( :'( now that the diode is dead, it shows FREAKING 130mA's!!! MY OLD DMM SAID 250 AND THAT ONE SEEMS TO HAVE BEEN CORRECT, yet now it has died, and this new one screwed me up. do dead LD's not intake as much current? i donno. im so bumed out right now... what is wrong? not the right load? i donno, i think im gonna order a replacement diode soon... ARGGG THIS IS SO FRUSTRATING

regards

amk

 

[Gazoo]

No wonder if you were taking amp readings with your meter in parallel...NEVER EVER do it that way.. ;D When measuring current your meter should be in series with the circuit.

 

[amkdeath]

No wonder if you were taking amp readings with your meter in parallel...NEVER EVER do it that way.. ;D When measuring current your meter should be in series with the circuit.

thats what i also did, but i get under 200 mA, mabe it has to do with something that chimo said, this is my DMM:
http://www.dealextreme.com/details.dx/sku.594

sigh...

 

[Gazoo]

Take my advice about the 1 ohm resistor..it is worth it And cheer up...things could always be worse. I know it sucks to lose our lovely diodes but there are plenty more where they came from and I know you will get another one and be happy.

 

[chimo]

Here's a start.

http://www.facstaff.bucknell.edu/mastascu/eLessonsHTML/Measurements/MeasIntro.htm#MeasuringCurrent

DMMs measure current by measuring the voltage drop across an internal shunt (resistance). The 10A scale has a very low resistance (good - little impact on the cct), the mA scale may have up to a couple of ohms resistance (bad - affects the circuit under test).

As gazoo pointed out, it is a bad idea to expose the LD to the transients you did by breaking the circuit to insert the multimeter. A better way to measure the current would have been to measure the voltage drop across the sense resistor for the LM317 and calculate the current or to measure the current on the battery side (in-line is OK on the *battery side*).

 

[Gazoo]

I agree with you...measuring on the battery side is the way to go. The 1 ohm resistor does make taking measurements more convenient.

 

[amkdeath]

I agree with you...measuring on the battery side is the way to go. The 1 ohm resistor does make taking measurements more convenient.

yet tahts 10x 10ohms in parallel (ouch)
time to go to digikey!

 

[Gazoo]

And make sure you get at least a 1 watt one...you may find a better deal on them on e-bay.

 

[amkdeath]

Here's a start.

http://www.facstaff.bucknell.edu/mastascu/eLessonsHTML/Measurements/MeasIntro.htm#MeasuringCurrent

DMMs measure current by measuring the voltage drop across an internal shunt (resistance).  The 10A scale has a very low resistance (good - little impact on the cct), the mA scale may have up to a couple of ohms resistance (bad - affects the circuit under test).  

As gazoo pointed out, it is a bad idea to expose the LD to the transients you did by breaking the circuit to insert the multimeter.  A better way to measure the current would have been to measure the voltage drop across the sense resistor for the LM317 and calculate the current or to measure the current on the battery side (in-line is OK on the *battery side*).

the link doesnt help. basically, from what i gather, my DMM is lying to me and that there really is more current???

 

[chimo]

[quote author=chimo link=1196824307/0#8 date=1196828188]Here's a start.

http://www.facstaff.bucknell.edu/mastascu/eLessonsHTML/Measurements/MeasIntro.htm#MeasuringCurrent

DMMs measure current by measuring the voltage drop across an internal shunt (resistance).  The 10A scale has a very low resistance (good - little impact on the cct), the mA scale may have up to a couple of ohms resistance (bad - affects the circuit under test).  

As gazoo pointed out, it is a bad idea to expose the LD to the transients you did by breaking the circuit to insert the multimeter.  A better way to measure the current would have been to measure the voltage drop across the sense resistor for the LM317 and calculate the current or to measure the current on the battery side (in-line is OK on the *battery side*).

the link doesnt help. basically, from what i gather, my DMM is lying to me and that there really is more current???
[/quote]

If it didn't help, you didn't read it closely enough. It doesn't lay it out on a silver platter. When you research something, try to gather lots of data and information and then piece together the best solution. You then have to filter out the bogus information (especially on the Web!!!!).

 

[amkdeath]

[quote author=amkdeath link=1196824307/0#12 date=1196829188][quote author=chimo link=1196824307/0#8 date=1196828188]Here's a start.

http://www.facstaff.bucknell.edu/mastascu/eLessonsHTML/Measurements/MeasIntro.htm#MeasuringCurrent

DMMs measure current by measuring the voltage drop across an internal shunt (resistance).  The 10A scale has a very low resistance (good - little impact on the cct), the mA scale may have up to a couple of ohms resistance (bad - affects the circuit under test).  

As gazoo pointed out, it is a bad idea to expose the LD to the transients you did by breaking the circuit to insert the multimeter.  A better way to measure the current would have been to measure the voltage drop across the sense resistor for the LM317 and calculate the current or to measure the current on the battery side (in-line is OK on the *battery side*).

the link doesnt help. basically, from what i gather, my DMM is lying to me and that there really is more current???
[/quote]

it teache sme how to measure current in series, i already knew that. tells me to keep DMM resistance as low as possible, doesnt help. How am i supposed to use this info to find out how much ma is being outputed in my driver? is it 180, or 250?

If it didn't help, you didn't read it closely enough. It doesn't lay it out on a silver platter. When you research something, try to gather lots of data and information and then piece together the best solution.  You then have to filter out the bogus information (especially on the Web!!!!). [/quote]

 

[Gazoo]

Do it like this:

Positive wire-------------------meter probe meter probe---------------------------------------Positive wire.

Got it.. ;D

You can do the same thing on the negative side and get the same results. Make sure your meter is hooked up and set correctly.