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# Thread: Stepping down from 5v to 3-4.5v

1. Hi everybody,

I have a cross line laser module to fit on my machine. My bob outputs a regulated 5v but the laser can only handle 3 to 4.5v.

I imagine I need some sort of inline resistor to drop the 5v to 4.5v?

Question is what value resistor?

or is there a better way?

I know I could use 3 x 1.5v batteries but I'd like an onboard solution I can control from a macro via Mach.

Many thanks for any and all help.

Regards, Jeff

2. I'll use three batteries and a relay.

Jeff

3. Just put a silicon diode (e.g. 1N4001) in series with the laser supply, it will drop a fairly consistant 0.7v. Use two, if you want to be on the safe side.

4. Originally Posted by BillTodd
Just put a silicon diode (e.g. 1N4001) in series with the laser supply, it will drop a fairly consistant 0.7v. Use two, if you want to be on the safe side.
Bill,

You have no idea how much I envy you and the others knowledge of electronics. I'm afraid I have a "nuts and bolts" brain and electrickery will always remain a dark art.

Thanks very much for the help guys, I'm off to find an 1N4001 and wire it in series.

Jeff.

5. Originally Posted by Smiler
Bill,

You have no idea how much I envy you and the others knowledge of electronics. I'm afraid I have a "nuts and bolts" brain and electrickery will always remain a dark art.

Thanks very much for the help guys, I'm off to find an 1N4001 and wire it in series.

Jeff.
Don't forget to wire it the right way round else your laser won't turn on! The diode casing has a white line at one end, this end needs to be more negative than the other (i.e. points to the -ve end of the supply) for current to flow.

Bill's solution is the simplest and easiest to get a 0.7v drop at up to 1A (for an 1N4001 diode, although any of the 1N400x range will do). If you need more than 1A then 1N5059 series is good for 2A and 1N5624 series for 3A.

6. Originally Posted by Smiler
Hi everybody,

I have a cross line laser module to fit on my machine. My bob outputs a regulated 5v but the laser can only handle 3 to 4.5v.

I imagine I need some sort of inline resistor to drop the 5v to 4.5v?

Question is what value resistor?

or is there a better way?

I know I could use 3 x 1.5v batteries but I'd like an onboard solution I can control from a macro via Mach.

Many thanks for any and all help.

Regards, Jeff
NOT FAIR !

I'v just recived mine from tiwan a few days ago, i was saving it to make a post about the idea of using one :). O Well :D

Check these out:

Inductors, Capacitors & Resistors

Components: Diodes, Resistors, Capacitors, Transistors & LED

You may also like this: Resistor Calculator

7. Originally Posted by Lee Roberts
NOT FAIR !

I'v just recived mine from tiwan a few days ago, i was saving it to make a post about the idea of using one :). O Well :D

Check these out:

Inductors, Capacitors & Resistors

Components: Diodes, Resistors, Capacitors, Transistors & LED

You may also like this: Resistor Calculator
Please carry on Lee. I'm sure there are quite a few members with routers who would be very interested in how you go about installing it. The macro is an easy one to write, to be honest the biggest headache is Screen4 (or Scream4 as some call it) and getting your screenset modded but once you have it working, it has got to be one of the most usefull things to add to a router.

Anyway,

I won't utter another word on the subject, forget I mentioned it everybody, in fact i don't even know what a laser is. :D

Jeff. (fast running out of inputs and outputs:p)

8. lolol. Will do, you feel free to post what you want mate. It will be a few week before i cang et to play with it.

9. <noob mode> What's the laser for? </noob mode>

Better to use 2 diodes in series - they can give a different voltage drop dependent on current flow.

If you don't need to run the laser for a long duration (assuming it's for alignment of some kind) the batteries/relay idea is safer.

10. Originally Posted by No1_sonuk
<noob mode> What's the laser for? </noob mode>

Better to use 2 diodes in series - they can give a different voltage drop dependent on current flow.

If you don't need to run the laser for a long duration (assuming it's for alignment of some kind) the batteries/relay idea is safer.
It is for setting the zero work coordinates. Useful on a router where absolute precision isn't needed (cutting a sign maybe). If I need precision, I use a touch probe.

Well, I've got a 5v regulated PSU and a relay board so I'll try your suggestion of the two diodes (100 just arrived from the Bay :) )

Thank you everyone for the help.

Jeff.

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