445/FlexModP3 Power Supply?

[paulzimm]

Hello, I am in the process of building a laser projector and I have two of these FlexModP3 drivers:
http://hacylon.case.edu/ebay/laser_diode/FlexModP3.php

One driver is used to power a 445 diode and the other will be used to power two LOC red diodes in series (each will get half the voltage). Now the FlexModP3 driver has a 1.5 volt drop (battery input versus output to LD) and I am currently using a rechargable lead-acid 6 volt battery which at full charge is just around 6.3 volts. I have tested this tonight and it works perfectly for my 445 diode because it keeps the output voltage just under 5 volts when pulling 1 amp. Tomorrow night I will test my two LOC red diodes in series with the other FlexModP3 driver.

Since the laser projector is for home use only, I don't want to always be charging the 6 volt battery and instead want to use an 'industrial grade' power supply like one of these:
5 Volt AC/DC Power Supplies, Low Power, 1 to 70 watts, Chassis and Enclosed

Problem is, almost all of these type of regulated power supplies are 5 volts. Will this work for me at 3.5 volts (5v - 1.5v drop) for my 445? I hear a lot about limiting the current on these forums but not too much about the voltage. Just how important is it that I give my 445 exactly 4.7 volts, and my LOC diodes 2.3 volts?

Any help is greatly appreciated!

 

[paulzimm]

I cannot find any decent 6 volt (+2 amp) power supplies so I am instead thinking of using something like this:
5 VOLT AC/DC POWER SUPPLY - RS-15-5, Mean Well RS-15-5
* The output can be adjusted up to 5.5 volts.

So 5.5 volts minus the 1.5 volt driver overhead is 4 volts TOTAL.

QUESTION: Is 4 volts enough to power a 445 blue diode and 2 volts enough to power each of my 2 LOC red diodes in series?

What is the MINIMUM voltage needed to power a 445 diode?

 

[DrSid]

Well .. you can't give both constant current and voltage .. one will always depend on the other, based on diode voltage/current curve. For diodes we use fixed current driver. It will change the voltage till the current is as required.
Fixed voltage driver will provide more and more current to keep the voltage as required .. that, if set wrongly, will kill the diode. And even if you preset it into correct voltage range, diode will lower its virtual resistance with temperature, driver will have to pump more current .. and again you will kill the diode.
So generally you don't use sources with stabilized voltage, which are common for electronics. You need special laser diode driver.

Minimum voltage varies a lot for each diode. Some people run it on 3.7V Lion battery direct drive.

 

[daguin]

Here's a plot done by IgorT

You can see that the 445nm diode needs 4-5V for even medium output

Peace,
dave

 

[paulzimm]

Right, I understand that the output of the driver needs to be around 4.5 volts but what about the INPUT voltage from the battery? Don't all these constant current drivers adjust the voltage based on the diodes voltage/current curve? I have tested some drivers being powered by only a 3 volt battery and seen that they are putting out over 4.5 volts at the diode.

You think I will be fine using a 5V power supply with a 445 diode using a FlexModP3 driver?

 

[DrSid]

Generally there are two types of drivers .. ones which lower the input voltage, other which increase it. Some drivers can even do both. So it's really hard to say. It should be part of the driver documentation.
Anyway it's not that for 4.5 output you need 5V input. Again, current plays the role. Generally diode takes power (voltage*current), and driver too takes power, and it needs a little more power, lets say 20% overhead. Let's say diode will take 4W (1A, 4V), and driver will take 5W. Some source can give that at 2.5V, 2A, some different source can do the same with 5V, 1A. And if you have driver which minimum working voltage is 4.5V, it will work with the second source, but not with the first.
Best would be to have driver documentation, to know required current, and to get the required voltage and current for driver feed from the documentation.

 

[Solonar]

2 LOC's in series would require ~6v from the driver, which means you would need at least 7.5V from the PSU.

 

[paulzimm]

I am almost positive the 5.5 volt PSU will work, here is the documentation of the driver:
http://hacylon.case.edu/laser/FlexModP3/FlexModP3_Manual.pdf

"It can accept input power in the range of VDiode + 1.5V up to 24V and the output voltage will match the load requirement."

 

[DrSid]

Yes, it looks good. Cool driver btw. Now only the input power source must provide enough power .. but imho it would be no problem.

 

[paulzimm]

Just purchased this 5.5vdc / 7 amps (35 Watt) power supply:
RS-35-5, Mean Well RS-35-5

Thanks for everyone's help - you are the BEST!

 

[DrSid]

Hey wait .. if the output voltage maxed at input voltage minus 1.5V, it will make 445nm diode lase, but not very well (check the graph). For one LOC it should be no problem .. for two it would be a big problem. Can you cancel it yet ? And wait for more people to react ?

 

[Solonar]

"It can accept input power in the range of VDiode + 1.5V up to 24V and the output voltage will match the load requirement."

What that means is that as long as you have enough input voltage, the output will match the diodes need, but if you don't give it enough voltage it will not supply enough output.

I had that issue with my FlexMods when I tried to drive a 405 with a 5V PSU. The driver would only supply ~4v to the diode. I now run a 12V PSU.

For 2 LOC's in series you have 2 X Vdiode of about 3V's each + 1.5V= 7.5V required.

 

[jaycey]

I use 2 Canon 8.4v 2A camera power supplies.

Dual LOC's & 445's

Dont but the cheap copies though, get an original Canon.

 

[paulzimm]

I use 2 Canon 8.4v 2A camera power supplies.

Dual LOC's & 445's

Dont but the cheap copies though, get an original Canon.

Would you happen to have a link please? Turns out my order for the 5.5 volt PSU did not go through...

 

[jaycey]

Search eBay for Canon CA-570

watch out for the copies though, I got mine for £12 used.


Edit: keep an eye on this one http://cgi.ebay.co.uk/Genuine-Canon...ctronics_PowerAdaptors_SM&hash=item4cf212b08a

 

[paulzimm]

Since the FlexModP3 accepts up to 24V (and just for the heck of it) I hooked up a fully charged 12V battery and connected it to my "dummy" load. The test load had a 1 Ohm resistor along with 4 diodes in series simulating a red laser diode. The FlexModP3 only provided the required voltage / current and would not have damaged a real laser diode had I connected it. Long story short, I can just get a 12V power supply and don't have to worry about messing with an under-powered 5.5V supply