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FrozenGate by Avery

What driver do you recommend for 1.5W?

So, now also ST distributes an Axelite equivalent ..... good to know, thanks.

rdh, different internal structures of the power element ..... this give you a higher current and a better heat dissipation .....

The only other important difference is that the lower current one is a little bit more "stable" in VOLTAGE regulation, but they does not indicate anything significative for the use we need for it (current drivers), so it must be tested.
 





RHD,
Specs on the 1084 say the Absolute Max voltage diff Vin to Gnd, or Vin to Vadj, is 7.0. So if I want to use two LiPo's (3.7*2), would I have to put a 1N540x in the Vin path?? Would that be enough drop??
 
123splat said:
RHD,
Specs on the 1084 say the Absolute Max voltage diff Vin to Gnd, or Vin to Vadj, is 7.0. So if I want to use two LiPo's (3.7*2), would I have to put a 1N540x in the Vin path?? Would that be enough drop??
Click to expand...

Are you looking at the correct thing? Max VI is 30V ... you cant have 30 volts without a 30 volt delta in relation to ground. 2 x 3.7V will be just fine.
 
jib77 said:
Are you looking at the correct thing? Max VI is 30V ... you cant have 30 volts without a 30 volt delta in relation to ground. 2 x 3.7V will be just fine.
Click to expand...

Maybe not, but what 1084 are you looking at and where do you get 30V in? The two that I have datasheets on show 12V and 7V as the max Vin.

Please see attached data sheets.
 

Attachments

I think the 7V figure means the difference between the input voltage, and the regulated output voltage when using it as a voltage regulator. IE - you couldn't expect to regulate a 25V supply down to 2V.

Either way, definitely doesn't apply here.
 
Sorry I haven't been active recently.... Been really busy. I see though that you have supplied me with LOTS of wonderful information. I am on my iPod and cannot do a full reply but tomorrow I will turn on the computer, I have a few more questions.

Thanks again!
 
I could be wrong... so please correct me. Can't you just run 2x lm317's in a parallel for a total output of 3000ma? I understand these would require alot of tweeking but it would be cheapest and you could sink them. Just a suggestion so please don't kill me if I am wrong.
 
Jib & RHD,
Looks like I need to dump the SMD ver.s and go with ST's TO-220's. Thanks for clarification and food for thought.
 
Ok, tonight i am ordering things for the laser. I was wondering if i used 3x CR2 batteries, in series to make 9v. I will then use these items:
Voltage Regulator: STMICROELECTRONICS|LD1084V|V REG ADJ 1.25/28V, 1084, TO-220 | Farnell United Kingdom
The 1N400N1 diode: Rectifier Diode : Diodes : Maplin
2x 10uF capcitors: SE Series Low Profile Radial Electrolytic Capacitors : Maplin
Potentiometer: POT 25 OHM 5W WIREWOUND W/HRDWAR - 026TB32R250B1A1

What resistor should i use if i want to have a 1.5A through. I have an idea where it has a continous power at 1.5A and i can pulse the laser at 2A, this way i will get a long life. What resistor should i get for 1.5A and what resistor for 2A?

Thanks
 
Better to go with 2 longer cells than 3 short cells, otherwise you will be wasting that 3rd cells power as heat. If you want to make 1.5-2amps what you need is high quality cells that can provide a 2A+ discharge rate. DO NOT use wire wound resistors and electrolytic caps, you will not have a stable driver. Ceramic caps are requires, wire wound means there is a coil which means you are introducing inductance into the circuit.

Edit: Resistor = 1.25 / Current in Amps
 
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Jib: resistor type recommendations?

(I feel like I learn from every post you make on the topic of driver design!)

I'm nicknaming you Dr. LavaRck 2
 
rhd said:
Jib: resistor type recommendations?

(I feel like I learn from every post you make on the topic of driver design!)

I'm nicknaming you Dr. LavaRck 2
Click to expand...

LOL ... A Dr. I am not. I'm just a lowly firmware coder with just enough knowledge to get myself in trouble.

I use SMDs, but film or carbon will work. Also some audio stores have something called non-inductive resistors for crossover circuits, these are a little more expensive but can handle a lot of wattage.
 
If you haven't decided already, you can check my sig for the link to my 445. It uses an 18650 battery and 1 flexdrive at 1.5A. If you have enough room to heatsink them, I would suggest using an 18650 (or bigger) battery and 2 flexdrives, each set to 800mA. This would give you 1.6A and depending on the diode's efficiency, about 1.5W output with an Aixiz 405/445 glass lens.
 
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