Laser pointer discussion. Read/write reviews of laser pointers and laser pointer companies. Learn about all types of laser pointers and lasers





Welcome to Laser Pointer Forums! If you are looking for a laser pointer or want to compare different laser pointer companies, you may want to check out the LPF Laser Pointer Company Database. The link will open in a new window for your convenience.








Green Laser Pointers by Category Blue Laser Pointers by Category Red Laser Pointers by Category
Yellow Laser Pointers by Category Violet Laser Pointers by Category Orange Laser Pointers by Category
Top Laser Pointers by Power - 1 Watt+ Top Laser Pointers by Power - 500mW+ Top Laser Pointers by Power - 250mW+
Laser Pointer Database High Power Laser Pointers Laser Pointer Diodes
Laser Technology Laser Pointer Parts Lasers by Wavelength
Top 10 Laser Pointer Companies Laser Pointer Company Database Visible Beam Laser Pointers


One laser store meets all your needs

























Go Back   Laser Pointer Forums - Discuss Laser Pointers > Lasers > Drivers, Test-load, Power Supply, & Batteries



LPF List of Laser Pointer Companies (link opens new window)



Reply
 
LinkBack Thread Tools Display Modes
Old 09-16-2012, 12:06 AM #1
EXO EXO is offline
Member
 
Join Date: Jul 2011
Posts: 31
Rep Power: 0
EXO is on a distinguished road
EXO EXO is offline
Member
 
Join Date: Jul 2011
Posts: 31
Rep Power: 0
EXO is on a distinguished road
Default NE555 PWM Buck Driver

Hi, I meant to do this type of driver for my new projects.It is very simple and very efficient.With this driver you can regulate output power from 5-95%.So you can adjust power output for laser diode which she need.Just worries me what will happen if the batteries are for example discharged to half, and here is no feedback circuit to regulate the PWM(ofc. you can manually do this with potentiometer P1,but it is not practical).What do you think if this is a smart solution for using as laser driver.
Attached Thumbnails
NE555 PWM Buck Driver-ne555-pwm-led-dimmer-circuit.gif  


EXO is offline   Reply With Quote







LPF List of Laser Pointer Companies (link opens new window)







Old 09-16-2012, 02:59 AM #2
Cyparagon's Avatar
Class 4 Laser
 
Join Date: Sep 2007
Location: Wisconsin
Posts: 9,142
Rep Power: 9321
Cyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond repute
Cyparagon Cyparagon is online now
Class 4 Laser
Cyparagon's Avatar
 
Join Date: Sep 2007
Location: Wisconsin
Posts: 9,142
Rep Power: 9321
Cyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond repute
Default Re: NE555 PWM Buck Driver

That's not a buck driver. It just pulses the LEDs, and it doesn't even have feedback or constant current operation. It isn't even constant voltage, since the pulse width will vary with the input voltage. It's about the same as using a pot as a driver.
__________________
A problem well stated is a problem half solved.
Cyparagon is online now   Reply With Quote
Old 09-16-2012, 04:43 AM #3
Meatball's Avatar
Class 3B Laser
 
Join Date: Feb 2008
Location: Lincoln, NE
Posts: 2,989
Rep Power: 242
Meatball has a reputation beyond reputeMeatball has a reputation beyond reputeMeatball has a reputation beyond reputeMeatball has a reputation beyond reputeMeatball has a reputation beyond reputeMeatball has a reputation beyond reputeMeatball has a reputation beyond reputeMeatball has a reputation beyond reputeMeatball has a reputation beyond reputeMeatball has a reputation beyond reputeMeatball has a reputation beyond repute
Meatball Meatball is offline
Class 3B Laser
Meatball's Avatar
 
Join Date: Feb 2008
Location: Lincoln, NE
Posts: 2,989
Rep Power: 242
Meatball has a reputation beyond reputeMeatball has a reputation beyond reputeMeatball has a reputation beyond reputeMeatball has a reputation beyond reputeMeatball has a reputation beyond reputeMeatball has a reputation beyond reputeMeatball has a reputation beyond reputeMeatball has a reputation beyond reputeMeatball has a reputation beyond reputeMeatball has a reputation beyond reputeMeatball has a reputation beyond repute
Default Re: NE555 PWM Buck Driver

^^A very fancy pot none the less.
__________________
FIAT LUX

(\__/)
(='.'=)
(")_(")
Meatball is offline   Reply With Quote
Old 09-16-2012, 06:28 AM #4
Jubathoph's Avatar
Class 1M Laser
 
Join Date: Jun 2011
Location: Los Angeles
Posts: 115
Rep Power: 21
Jubathoph has much to be proud ofJubathoph has much to be proud ofJubathoph has much to be proud ofJubathoph has much to be proud ofJubathoph has much to be proud ofJubathoph has much to be proud ofJubathoph has much to be proud ofJubathoph has much to be proud ofJubathoph has much to be proud ofJubathoph has much to be proud of
Jubathoph Jubathoph is offline
Class 1M Laser
Jubathoph's Avatar
 
Join Date: Jun 2011
Location: Los Angeles
Posts: 115
Rep Power: 21
Jubathoph has much to be proud ofJubathoph has much to be proud ofJubathoph has much to be proud ofJubathoph has much to be proud ofJubathoph has much to be proud ofJubathoph has much to be proud ofJubathoph has much to be proud ofJubathoph has much to be proud ofJubathoph has much to be proud ofJubathoph has much to be proud of
Default Re: NE555 PWM Buck Driver

ok dude you are almost there. instead of driving the diode with this circuit, use the mosfet to switch current to the negative of a DRIVER. then hook the driver to your diode. the problem you have is the PWM is not regulating current. hence the need for a driver. make sure you pick your capacitor such that the frequency isn't too high. 100hz is good. if your pot is adjustable you will have a nice dimmable laser.
Jubathoph is offline   Reply With Quote
Old 09-16-2012, 07:26 AM #5
Bionic-Badger's Avatar
Class 4 Laser
 
Join Date: Oct 2007
Location: Oregon, USA
Posts: 5,478
Rep Power: 2192
Bionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond repute
Bionic-Badger Bionic-Badger is online now
Class 4 Laser
Bionic-Badger's Avatar
 
Join Date: Oct 2007
Location: Oregon, USA
Posts: 5,478
Rep Power: 2192
Bionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond repute
Default Re: NE555 PWM Buck Driver

Using PWM does have the benefit of linearizing the brightness of the output instead of relying on just regulating current--though it can add flicker. Then again, a lot of the diode's output power is linear with respect to current.
__________________
You must spread some Reputation around before giving it to <person> again.
Bionic-Badger is online now   Reply With Quote
Old 09-16-2012, 01:09 PM #6
EXO EXO is offline
Member
 
Join Date: Jul 2011
Posts: 31
Rep Power: 0
EXO is on a distinguished road
EXO EXO is offline
Member
 
Join Date: Jul 2011
Posts: 31
Rep Power: 0
EXO is on a distinguished road
Default Re: NE555 PWM Buck Driver

Look if you can dim led why not to dim laser diode.I never care about current regulation,I only care about maximal diode current.Good cooler resolve thermal runway so I dont need constant current driver.My problem is that I use 3x1.5v batteries (4.5V) to drive blue laser diode @ 4.8v.So I cant use buck or boost converter because such a small difference in voltage.Linear driver have big voltage drop for this use.
I think use this "driver" because she can regulate output power without significant voltage drop(Rds on mosfet is low).I use this driver to regulate DC motors so why not laser diode.Ofc. I put capacitor on output so there is no flicker.
EXO is offline   Reply With Quote
Old 09-16-2012, 02:01 PM #7
Cyparagon's Avatar
Class 4 Laser
 
Join Date: Sep 2007
Location: Wisconsin
Posts: 9,142
Rep Power: 9321
Cyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond repute
Cyparagon Cyparagon is online now
Class 4 Laser
Cyparagon's Avatar
 
Join Date: Sep 2007
Location: Wisconsin
Posts: 9,142
Rep Power: 9321
Cyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond repute
Default Re: NE555 PWM Buck Driver

Quote:
Originally Posted by EXO View Post
I never care about current regulation


Lasers don't take abuse like LEDs do. You have a lesson to learn here. If you want to learn it the expensive way, so be it.
__________________
A problem well stated is a problem half solved.
Cyparagon is online now   Reply With Quote
Old 09-16-2012, 02:05 PM #8
lasersbee's Avatar
Class 4 Laser
 
Join Date: Sep 2008
Location: Quebec, Canada
Posts: 15,709
Rep Power: 40049
lasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond repute
lasersbee lasersbee is offline
Class 4 Laser
lasersbee's Avatar
 
Join Date: Sep 2008
Location: Quebec, Canada
Posts: 15,709
Rep Power: 40049
lasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond repute
Default Re: NE555 PWM Buck Driver

Quote:
Originally Posted by EXO View Post
Hi, I meant to do this type of driver for my new projects.It is very simple and very efficient.With this driver you can regulate output power from 5-95%.So you can adjust power output for laser diode which she need.Just worries me what will happen if the batteries are for example discharged to half, and here is no feedback circuit to regulate the PWM(ofc. you can manually do this with potentiometer P1,but it is not practical).What do you think if this is a smart solution for using as laser driver.
If you use the Current limiting Resistors as are used on the
LEDs to limit the maximum current to the LD depending on
your MAX supply voltage to the 555 circuit there should be
no problem to use that circuit for brightness control.


Jerry

You can contact us at any time on our Website: J.BAUER Electronics
__________________

J.BAUER Electronics Home Page

LaserBee Laser Power Meter Products meet your needs
at affordable Prices:
See them all here on LPF

LaserBee Power Meter products ALWAYS in Stock
and ready to ship

Also available on eBay:Check availability here..

Subsidary: Pharma Electronic Solutions


This banner is available to and can be copied/used FREE by any LaserBee owner

Last edited by lasersbee; 09-16-2012 at 02:07 PM.
lasersbee is offline   Reply With Quote
Old 09-16-2012, 03:08 PM #9
EXO EXO is offline
Member
 
Join Date: Jul 2011
Posts: 31
Rep Power: 0
EXO is on a distinguished road
EXO EXO is offline
Member
 
Join Date: Jul 2011
Posts: 31
Rep Power: 0
EXO is on a distinguished road
Default Re: NE555 PWM Buck Driver

Quote:
Lasers don't take abuse like LEDs do. You have a lesson to learn here. If you want to learn it the expensive way, so be it.

In previous laser projects, I never used the constant current driver.I always(ultra) use constant voltage control (i.e. LM1117,MC34063).Because if is laser diode rated for example 3V @ 100mA,they will not pull more current if you apply 3V.Ofc. they will pull more current if heatsink is bad(thermal runway) or you apply more voltage.So I regulate current with voltage.I have not a single diode destroyed in this way.
But in this project problem is very little difference in voltage.
EXO is offline   Reply With Quote
Old 09-16-2012, 05:54 PM #10
rhd's Avatar
rhd rhd is offline
Class 4 Laser
 
Join Date: Dec 2010
Posts: 8,491
Rep Power: 1392
rhd has a reputation beyond reputerhd has a reputation beyond reputerhd has a reputation beyond reputerhd has a reputation beyond reputerhd has a reputation beyond reputerhd has a reputation beyond reputerhd has a reputation beyond reputerhd has a reputation beyond reputerhd has a reputation beyond reputerhd has a reputation beyond reputerhd has a reputation beyond repute
rhd rhd is offline
Class 4 Laser
rhd's Avatar
 
Join Date: Dec 2010
Posts: 8,491
Rep Power: 1392
rhd has a reputation beyond reputerhd has a reputation beyond reputerhd has a reputation beyond reputerhd has a reputation beyond reputerhd has a reputation beyond reputerhd has a reputation beyond reputerhd has a reputation beyond reputerhd has a reputation beyond reputerhd has a reputation beyond reputerhd has a reputation beyond reputerhd has a reputation beyond repute
Default Re: NE555 PWM Buck Driver

Quote:
Originally Posted by EXO View Post
In previous laser projects, I never used the constant current driver.I always(ultra) use constant voltage control (i.e. LM1117,MC34063).Because if is laser diode rated for example 3V @ 100mA,they will not pull more current if you apply 3V.Ofc. they will pull more current if heatsink is bad(thermal runway) or you apply more voltage.So I regulate current with voltage.I have not a single diode destroyed in this way.
But in this project problem is very little difference in voltage.
Because ratings are always accurate?

A) We don't have clear spec sheets for most of the 445s out there, because we're generally not buying them as virgin diodes.

B) Even if we did, they vary from diode to diode. Some 445s have substantially higher Vf ratings (+/- as much as 0.5V in some of the tests I've seen) than others.

C) When your Voltage curve is relatively flat, a very small variance in voltage can produce a relatively larger variance in current.

D) It's questionable to use Voltage regulation with a pot. But it's downright nuts to use Voltage regulation with fixed resistors. With a pot, at least you're adjusting the voltage, while (hopefully) monitoring current, and then leaving it set at a setting that produces an appropriate mA figure. With fixed resistors, you're just praying that the IV curve of your particular diode matches what you're planning for based on a datasheet, and that your voltage, set with fixed resistors, corresponds to an appropriate current on your specific diode's curve.
__________________
CURRENT WAVELENGTHS:
405|441|450|467|473|495|505|520|532|556|PGLRG|589|594|632|638|660


SAFETY & IMPORTANT READING (threads authored and contributed to by various members of LPF):
- Federal Aviation Administration - Laser Safety Initiative (link)
- Info release from Laserglow - Default Canadian restrictions on portable lasers (link)
- The Necessity of Safety Goggles (link)


Last edited by rhd; 09-16-2012 at 05:55 PM.
rhd is offline   Reply With Quote
Old 09-16-2012, 06:52 PM #11
Bionic-Badger's Avatar
Class 4 Laser
 
Join Date: Oct 2007
Location: Oregon, USA
Posts: 5,478
Rep Power: 2192
Bionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond repute
Bionic-Badger Bionic-Badger is online now
Class 4 Laser
Bionic-Badger's Avatar
 
Join Date: Oct 2007
Location: Oregon, USA
Posts: 5,478
Rep Power: 2192
Bionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond repute
Default Re: NE555 PWM Buck Driver

Quote:
Originally Posted by EXO View Post
In previous laser projects, I never used the constant current driver.I always(ultra) use constant voltage control (i.e. LM1117,MC34063).Because if is laser diode rated for example 3V @ 100mA,they will not pull more current if you apply 3V.Ofc. they will pull more current if heatsink is bad(thermal runway) or you apply more voltage.So I regulate current with voltage.I have not a single diode destroyed in this way.
But in this project problem is very little difference in voltage.
So let me get this straight: you're going to rely on the non-linear, temperature-dependent I-V curves of a diode and regulate the voltage with millivolt or even microvolt precision to regulate the current (the important parameter affecting output power), and all this without active temperature control, or feedback for that matter (assuming it even converges)?

Well good luck with that dude.

This all reminds me of Jeff Goldblum explaining chaos theory in Jurassic Park.

__________________
You must spread some Reputation around before giving it to <person> again.
Bionic-Badger is online now   Reply With Quote
Old 09-16-2012, 07:36 PM #12
EXO EXO is offline
Member
 
Join Date: Jul 2011
Posts: 31
Rep Power: 0
EXO is on a distinguished road
EXO EXO is offline
Member
 
Join Date: Jul 2011
Posts: 31
Rep Power: 0
EXO is on a distinguished road
Default Re: NE555 PWM Buck Driver

Yes.I dont know what is so heavy.Simply use lm1117 linear regulator and connect it in voltage regulation.Turn trimmer on lowest output voltage and connect laser diode(in heatsink).Then simply increase voltage and in same time monitor current.When I reach desired current for laser diode I stop increase voltage.And that's it.

Last edited by EXO; 09-16-2012 at 07:37 PM.
EXO is offline   Reply With Quote
Old 09-16-2012, 08:12 PM #13
Meatball's Avatar
Class 3B Laser
 
Join Date: Feb 2008
Location: Lincoln, NE
Posts: 2,989
Rep Power: 242
Meatball has a reputation beyond reputeMeatball has a reputation beyond reputeMeatball has a reputation beyond reputeMeatball has a reputation beyond reputeMeatball has a reputation beyond reputeMeatball has a reputation beyond reputeMeatball has a reputation beyond reputeMeatball has a reputation beyond reputeMeatball has a reputation beyond reputeMeatball has a reputation beyond reputeMeatball has a reputation beyond repute
Meatball Meatball is offline
Class 3B Laser
Meatball's Avatar
 
Join Date: Feb 2008
Location: Lincoln, NE
Posts: 2,989
Rep Power: 242
Meatball has a reputation beyond reputeMeatball has a reputation beyond reputeMeatball has a reputation beyond reputeMeatball has a reputation beyond reputeMeatball has a reputation beyond reputeMeatball has a reputation beyond reputeMeatball has a reputation beyond reputeMeatball has a reputation beyond reputeMeatball has a reputation beyond reputeMeatball has a reputation beyond reputeMeatball has a reputation beyond repute
Default Re: NE555 PWM Buck Driver

But temperature will change as current flows through the diode, which also affects its Vf/A "ratings". Seriously, electrical conduction through the junction of a diode is much more complicated than by regulating some voltage. Small LEDs and LDs don't deal with this sort of thing as much since they do not generate very much heat.

This diode you're trying to run is sinking over 1000mA across a junction with a 4.5V voltage drop. You CANNOT regulate the dissipation of 5W of heat without some kind of active cooling mechanism in such a small space.

You come here and ask us if this is a smart solution to driving a laser diode, and we tell you the truth - now all you want to do is fight the truth instead of accepting what you asked for. You can either admit that the circuit is not adequate, and you could let us help you make a better one, or you can ignore the entire forum of hobbiests that do this stuff all the time, and then come back asking us for help when your device stops working the way you wanted it to.

Either take what we have to offer you, or run without it. Your argument has no weight on this one.
__________________
FIAT LUX

(\__/)
(='.'=)
(")_(")
Meatball is offline   Reply With Quote
Old 09-16-2012, 10:16 PM #14
Bionic-Badger's Avatar
Class 4 Laser
 
Join Date: Oct 2007
Location: Oregon, USA
Posts: 5,478
Rep Power: 2192
Bionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond repute
Bionic-Badger Bionic-Badger is online now
Class 4 Laser
Bionic-Badger's Avatar
 
Join Date: Oct 2007
Location: Oregon, USA
Posts: 5,478
Rep Power: 2192
Bionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond repute
Default Re: NE555 PWM Buck Driver

Well... some people have to stare into the sun to learn that they can become blind...
__________________
You must spread some Reputation around before giving it to <person> again.
Bionic-Badger is online now   Reply With Quote
Old 09-16-2012, 11:07 PM #15
lasersbee's Avatar
Class 4 Laser
 
Join Date: Sep 2008
Location: Quebec, Canada
Posts: 15,709
Rep Power: 40049
lasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond repute
lasersbee lasersbee is offline
Class 4 Laser
lasersbee's Avatar
 
Join Date: Sep 2008
Location: Quebec, Canada
Posts: 15,709
Rep Power: 40049
lasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond repute
Default Re: NE555 PWM Buck Driver

Quote:
Originally Posted by EXO View Post
In previous laser projects, I never used the constant current driver.I always(ultra) use constant voltage control (i.e. LM1117,MC34063).Because if is laser diode rated for example 3V @ 100mA,they will not pull more current if you apply 3V.Ofc. they will pull more current if heatsink is bad(thermal runway) or you apply more voltage.So I regulate current with voltage.I have not a single diode destroyed in this way.
But in this project problem is very little difference in voltage.
It seems you don't really grasp the reasons why a Current Regulated
Driver is preferred to a Volage Regulated driver that you seem to beleive
is a better choice.

I'll try to explain the problems with a Voltage regulated driver in basic
terms.
Lets say that......

1) you have a regulated Voltage driver outputting 4 Volts to a Laser
Diode and it runs fine when first turned "on".

2) as the LD warms up the internal resistance decreases and at 4 volts
now draws more current reducing the Voltage that the Regulator sees.

3) to compensate the Voltage regulator increases its voltage to maintain
the original 4Volts to the increased LD load (decreased internal resistance)
due to internal heating.

4) this now increases the internal heat of the LD even more... and you
are now in a loop to item 2)

This continues until there is a catastrophic failure or power is turned off
to cool the LD and return it to its original cold internal resistance.

I've been on the Forum for 4 years and have heard all the reasons why
Voltage regulators work best.

Simple Answer............

A Laser Diode is a sensitive Current Device and needs/requires a Current
Regulated Driver.


Jerry

You can contact us at any time on our Website: J.BAUER Electronics
__________________

J.BAUER Electronics Home Page

LaserBee Laser Power Meter Products meet your needs
at affordable Prices:
See them all here on LPF

LaserBee Power Meter products ALWAYS in Stock
and ready to ship

Also available on eBay:Check availability here..

Subsidary: Pharma Electronic Solutions


This banner is available to and can be copied/used FREE by any LaserBee owner

Last edited by lasersbee; 09-17-2012 at 05:37 PM.
lasersbee is offline   Reply With Quote
Old 09-16-2012, 11:09 PM #16
EXO EXO is offline
Member
 
Join Date: Jul 2011
Posts: 31
Rep Power: 0
EXO is on a distinguished road
EXO EXO is offline
Member
 
Join Date: Jul 2011
Posts: 31
Rep Power: 0
EXO is on a distinguished road
Default Re: NE555 PWM Buck Driver

Quote:
Originally Posted by Meatball View Post
But temperature will change as current flows through the diode, which also affects its Vf/A "ratings". Seriously, electrical conduction through the junction of a diode is much more complicated than by regulating some voltage. Small LEDs and LDs don't deal with this sort of thing as much since they do not generate very much heat.

This diode you're trying to run is sinking over 1000mA across a junction with a 4.5V voltage drop. You CANNOT regulate the dissipation of 5W of heat without some kind of active cooling mechanism in such a small space.

You come here and ask us if this is a smart solution to driving a laser diode, and we tell you the truth - now all you want to do is fight the truth instead of accepting what you asked for. You can either admit that the circuit is not adequate, and you could let us help you make a better one, or you can ignore the entire forum of hobbiests that do this stuff all the time, and then come back asking us for help when your device stops working the way you wanted it to.

Either take what we have to offer you, or run without it. Your argument has no weight on this one.
My diode have 300mW not 5W.I talk about my experience with constant voltage regulators.I have tested constant current drivers and have and I have not noticed any difference between.I prefer constant voltage because it is simple to make and is more efficiency(no sensing resistors).
And if is so bad constant voltage because any of my laser pointer dont die?I have many of them an no one die from over heating or thermal runway.

Last edited by EXO; 09-16-2012 at 11:17 PM.
EXO is offline   Reply With Quote
Reply





Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


LinkBacks (?)
LinkBack to this Thread: http://laserpointerforums.com/f67/ne555-pwm-buck-driver-77376.html
Posted By For Type Date
NE 555 | Referanser på Internett | cyclopaedia.net This thread Refback 04-24-2014 04:25 PM
?????-???????? : buck NE555 This thread Refback 01-19-2013 08:37 PM










Loading








Green Laser Pointers by Category Blue Laser Pointers by Category Red Laser Pointers by Category
Yellow Laser Pointers by Category Violet Laser Pointers by Category Orange Laser Pointers by Category
Top Laser Pointers by Power - 1 Watt+ Top Laser Pointers by Power - 500mW+ Top Laser Pointers by Power - 250mW+
Laser Pointer Database High Power Laser Pointers Laser Pointer Diodes






Privacy Policy | Advertising Disclaimer | Terms of Use


 


All times are GMT. The time now is 03:55 AM.


Powered by: vBulletin
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO
Privacy Policy | Advertising Disclaimer | Terms of Use
Copyright (C) 2017 Laser Pointer Forums, LLC