CR123A housing HAS blue ray.

[Gazoo]

Re: CR123A housing awaits blue ray.

Well I think you will have much better luck with lithiums. I have not tried them in the LPM-1..in fact I am using the same battery in it as the day I received it, but I know you use yours more. I don't know of any other battery that would be better that would fit in the battery compartment, but if you find a better solution I am all ears.. I thought about making a battery pack and attaching it to the back of the meter.

I will be looking forward to an alternative power source for the blu-ray. A boost/buck circuit or something along those lines would be ideal.

 

[zerafiel]

Re: CR123A housing awaits blue ray.

7805 is [smiley=thumbdown.gif]

The voltage input makes a HUGE difference for the drive current... and in a situation where the 7805 gets a nice spike of about 15V on initial battery discharge, the current going into the diode could fry it instantly! :-/

--DDL

Just want to check here. What are typical battery spikes for say 2 cr123 or rcr123? If it is 15V or more some regulators might not be able to handle them.

 

[Gazoo]

Re: CR123A housing awaits blue ray.

Daedal was testing it as a current regulator...using it as a voltage regulator will not be a problem.

 

[zerafiel]

Re: CR123A housing awaits blue ray.

Actually I was asking what the battery spike was to the Vin of the regulator and not at the output.

But even if you spike 15v through the 7805, it should be able to handle it(35v max) and the reference will still be 5v across the resistor. I don"t see why the current would change since it is fixed. Only the voltage across the diode would be much much higher and still fry the diode.

 

[rog8811]

Re: CR123A housing awaits blue ray.

*gets back from work....looks at how busy thread has been....goes to lay down in a darkened room*

Hi guys, lots of new info but it looks like I have ordered the right stuff...I just need to check what value caps I have around.....oh and I will get out the shoehorn to fit it all into my module....

Regards rog8811

 

[Gazoo]

Re: CR123A housing awaits blue ray.

Yup, but now we are going to use it as a voltage regulator with the resistor in series with the diode. Please do not attempt to use it as a current regulator.....this is dangerous.

 

[rog8811]

Re: CR123A housing awaits blue ray.

Thanks Gazoo,I am almost glad you guys got your bits first, you have saved me a load of heartache constant voltage it is!
I have sorted out a 1ohm res for testing, my vr is a 100ohm 25turn, will that do the trick?

Regards rog8811

 

[zerafiel]

Re: CR123A housing awaits blue ray.

Hey rog I am thinking you will need 10-15ohms if you run the pot in series to the diode. so a 25 turn 100ohm might not cut it unless I am calculating it wrongly. Check with gazoo before running to see what he uses. I am waiting to see if this works well too.

 

[rog8811]

Re: CR123A housing awaits blue ray.

I am thinking you will need 10-15ohms if you run the pot in series to the diode

I have a few other choices of trim pot....I think, I am waiting with bated breath to get a range of resistance from other builders to see where I need to go.

Regards rog8811

*Edit, just re-read the thread, do I need to be using tant caps on this? will poly's do?

 

[Gazoo]

Re: CR123A housing awaits blue ray.

Hey rog I am thinking you will need 10-15ohms if you run the pot in series to the diode. so a 25 turn 100ohm might not cut it unless I am calculating it wrongly. Check with gazoo before running to see what he uses. I am waiting to see if this works well too.

Why wouldn't a 100 ohm trim pot work? It is adjustable from 0 ohms to 100 ohms. I will be using a 50 ohm multi-turn trim pot.

Rog, I don't see why the capacitor on the input side would be critical. But the one that goes across the diode is. I will be using a 10uf 16 volt across the diode.

Daedal did suggest using a 100uf on the input side, but IMO it isn't necessary with batteries. I am sticking to a .33uf on the input side, but the value is not critical and really is only needed if the power supply is a distance away from the regulator. But I will be using them anyway.

 

[zerafiel]

Re: CR123A housing awaits blue ray.

Well I was thinking with a resolution of 4ohm per turn and 10% tolerance. Maybe you can be accurate up to half a turn but that is still 2ohms and the voltage range is estimated 10-15ohms. So perhaps 50 ohm 25 turn might be more precise up to 1ohm per half turn.
But these pots are like 10mm tall.

 

[rog8811]

Re: CR123A housing awaits blue ray.

....I wasn,t thinking the 10mf 16v already in the circuit is the output side cap, no need for another one...I think I may have some.33's.


Regards rog8811

*Edit, Circuit redrawn with push button in its rightful place

 

[Gazoo]

Re: CR123A housing awaits blue ray.

The regulator does draw a small amount of current...I think 5 to 6 ma's. So...either find a way to put the switch before the regulator, or take the batteries out when you are not using it.. I did get my regulators and capacitors today, and I might get the trim pots tomorrow. If I do I can put this together and let you know how it works out...

 

[Gazoo]

Re: CR123A housing awaits blue ray.

I did a quick and dirty build with the little 5 volt regulators we ordered. I put a 1 ohm resistor in series so I could measure current, then put one of my rheostat in series with it.

According to my readings, my diode measures ~40ma's with ~6ohms resistance, and ~30ma's with ~13 ohms resistance. The regulator does not get the least bit warm. Anyway, just thought you would like to know..and of course your millage may vary some depending on your diode.

Added: I settled on a 9.7 ohm resistor in series with my 1 ohm resistor. This gives me a reading of 37ma's. I do not have a variable voltage supply. However, I dropped the voltage to 6.5 volts and the diode was still lasing nicely with 30ma's.

BTW, a 1/4 watt resistor works fine...doesn't get warm or anything.

 

[rog8811]

Re: CR123A housing awaits blue ray.

My regulators arrived I decided to do some surgery to get the switch between batteries and the circuit so I had to put the reg down the back of the switch....It fits....just!

another pici follows

 

[rog8811]

Re: CR123A housing awaits blue ray.

....not the prettiest circuit I have ever built but it works OK, here it is in the module.

Regards rog8811