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Polarity?

Richie89

Richie89

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Okay I've always had some questions about things that I always have a hard time finding, one of them is.
Most lasers I've always dealt with had the polarity usually positive toward diode. But I have a couple lasers where the positive is toward tailcap. I though on DC current energy flowed negative to positive, so would that make the current go toward tailcap? I don't quite understand. Thanks for help.
 





ElectricPlasma

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It doesn't have much to do with the way electricity flows, it's how the laser itself is designed. All hosts (or at least the majority of them) carry a polarity via the case material, that's how the end of the battery connects to the tailcap to complete the circuit. What determines the way a battery is put in is what signal is carried via the case, for example whether the host is "case positive" or "case negative." Let's say we've got a host that's case positive, in that case (pun intended) the battery's positive terminal would be towards the tailcap. And vice versa if the host is case ground. If the positive terminal of the battery goes toward the diode, the host is case negative. :)

Good on you for being attentive to this information, not all lasers have reverse polarity protection and can get fried if the battery is inserted in the wrong direction.
 
paul1598419

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A good example of a case positive diode is the IR 808nm diodes. They are used especially in the DPSSL 532nm builds. Since the case of the 808nm diode is positive, it is necessary to have a continuous positive driver to drive it and the negative contact for the battery is switched through the, or to the, driver. This makes the case positive out of necessity.
 
Pi R Squared

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Yes it's true Current flows negative to positive, but that doesn't necessarily have anything to do with how things are wired. Some red diodes are case negative, I think all IR diodes and DPSS modules are case positive, most or all of the rest are case neutral, that means they can be wired either way, depending on what parts are used of course.

Alan
 
paul1598419

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Actually, electrons flow negative to positive. Current, by convention flows positive to negative. That's why diodes have an arrow pointing in the direction of current flow, positive to negative. The reason for this is because the math involved with AC current is more easily resolved by this convention. If fact, many equations just work easier this way.
 
Pi R Squared

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paul1598419 said:
Actually, electrons flow negative to positive. Current, by convention flows positive to negative. That's why diodes have an arrow pointing in the direction of current flow, positive to negative. The reason for this is because the math involved with AC current is more easily resolved by this convention. If fact, many equations just work easier this way.
Click to expand...

Current is the flow of electrons. They can only flow from negative to positive.

Alan
 
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Richie89

Richie89

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ElectricPlasma said:
It doesn't have much to do with the way electricity flows, it's how the laser itself is designed. All hosts (or at least the majority of them) carry a polarity via the case material, that's how the end of the battery connects to the tailcap to complete the circuit. What determines the way a battery is put in is what signal is carried via the case, for example whether the host is "case positive" or "case negative." Let's say we've got a host that's case positive, in that case (pun intended) the battery's positive terminal would be towards the tailcap. And vice versa if the host is case ground. If the positive terminal of the battery goes toward the diode, the host is case negative. :)

Good on you for being attentive to this information, not all lasers have reverse polarity protection and can get fried if the battery is inserted in the wrong direction.
Click to expand...

Oh okay. Yeah that makes sense, it always kinda confused me a little. especially when building my own, definitely need to know this information. Thanks a lot
 
Richie89

Richie89

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paul1598419 said:
A good example of a case positive diode is the IR 808nm diodes. They are used especially in the DPSSL 532nm builds. Since the case of the 808nm diode is positive, it is necessary to have a continuous positive driver to drive it and the negative contact for the battery is switched through the, or to the, driver. This makes the case positive out of necessity.
Click to expand...

Oh yeah because my case positive lasers are actually 532 which of course is 808nm. Ahh it's all coming together :D
 
Richie89

Richie89

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Pi R Squared said:
Yes it's true Current flows negative to positive, but that doesn't necessarily have anything to do with how things are wired. Some red diodes are case negative, I think all IR diodes and DPSS modules are case positive, most or all of the rest are case neutral, that means they can be wired either way, depending on what parts are used of course.

Alan
Click to expand...

yeah I started reading all kinds of stuff on dpss and 532nm. Green is a lot more interesting than I though. Makes me wants a powerful 532nm even more
 
Richie89

Richie89

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paul1598419 said:
Actually, electrons flow negative to positive. Current, by convention flows positive to negative. That's why diodes have an arrow pointing in the direction of current flow, positive to negative. The reason for this is because the math involved with AC current is more easily resolved by this convention. If fact, many equations just work easier this way.
Click to expand...

Definitely true, electronic confuses me I try learning all I can. sometimes my math is not so good, I'll just leave that to you guys lol.
 
RedCowboy

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There is no hard and fast rule, you need to make sure with each unit.

Most our big blue MM diodes are case neutral, you could energize the housing either way.
 
Richie89

Richie89

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RedCowboy said:
There is no hard and fast rule, you need to make sure with each unit.

Most our big blue MM diodes are case neutral, you could energize the housing either way.
Click to expand...

Oh okay yeah that's what I was wondering about. I needed to figure this out because I was soon gonna build my own and wanted to make sure I didn't make a first time mess up and be slightly embarrassed lol.
 
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