Driver Circuit Thread

[rhd]

Hey rhd, you have to right click the lm358, click invoke, then click the power option. For whatever reason they set it to be available by request.

Brilliant.

Thank you Ben. I had a feeling the problem was user-based

That worked perfectly. +1
(EDIT: Must spread first)

 

[Sigurthr]

So many schematics in one thread... This thread should be renamed "The EEporn Thread" XD.

I've never used Eagle, but I like how it's layout looks. Is it hard to get used to from basic freeware like ExpressPCB?

 

[rhd]

So many schematics in one thread... This thread should be renamed "The EEporn Thread" XD.

I've never used Eagle, but I like how it's layout looks. Is it hard to get used to from basic freeware like ExpressPCB?

Nope, it's incredibly simple. It's helpful to have people like Ben and others on the forum around that can get you out of binds though Some things are not totally intuitive.

But the learning curve is really not bad at all.

 

[benmwv]

Eagle takes a bit to get everything down, but once you get the hang of it it's very easy to use. Ive been using eagle for close to a year now and I still learn new things about it here and there.

 

[tsteele93]

So my brain is starting to fry a little from this (and other similar threads). I came here looking for the easiest (reasonably priced) way to take an Ophir head and put together the rest of the package to build an LPM out of it.

Am I in the right place, or can someone point me in that direction? Thanks!

 

[rhd]

So my brain is starting to fry a little from this (and other similar threads). I came here looking for the easiest (reasonably priced) way to take an Ophir head and put together the rest of the package to build an LPM out of it.

Am I in the right place, or can someone point me in that direction? Thanks!

Well- I built a derivative of Jib77's circuit, and it didn't work.

That said, it's entirely possible that this was an error in my own implementation. But I haven't yet been able to spot where I went wrong.

Here's my schematic, meant to be used with an input of 4x lithium ions.

 

[tsteele93]

Is that from this thread? http://laserpointerforums.com/f51/help-ophir-head-panel-meter-1-battery-68648-2.html

I didn't meant to split things up if it is, I just found it too. My brain is mush tonight. I had to watch the kids (they say you can't call it babysitting if you are the dad) while my wife went to some painting class tonight.

I watched HOP twice, broke up half-a-dozen fights and ate Easter eggs for dinner.

My IQ is several points lower right now, and reading all of these posts makes me realize I don't really have that many to spare.

 

[Cyparagon]

Didn't work how? What do the terminal names stand for? Not all of them are obvious to me.

 

[lazeerer]

Well- I built a derivative of Jib77's circuit, and it didn't work.

That said, it's entirely possible that this was an error in my own implementation. But I haven't yet been able to spot where I went wrong.

Here's my schematic, meant to be used with an input of 4x lithium ions.

I sent it over to Rick to have a Look.

Ill email you when he gets back to me.:beer:

 

[rhd]

Didn't work how? What do the terminal names stand for? Not all of them are obvious to me.

I sent it over to Rick to have a Look.

Ill email you when he gets back to me.:beer:

Most of those terminal names are non-essential. You can ignore BMTR and CHR. Those are basically just duplications of wirepads so that I can add other features to my box later. SW just closes the V+ circuit (it's for a switch)

The core wirepads here are:
- The LXXX pads along the top, which go to the 4 leads on the LED panel
- The OXXX pads along the right, which go to the Ophir
- The V+ and V- along the left, which provide the input voltage from 4x lithium ions.

Here's the explanation of the circuit:
- Basically, there's a fixed 5V LDO regulator for the LED panel, and a fixed 12V LDO regulator to provide 12V input into what is essentially (I think) an exact copy of Jib's circuit.

Here's the problem:
- In practice, I got a split rail, but not an EVENLY split rail. The result was -4.5 and +7.5. It still added up to a perfect 12V, but it wasn't split evenly. It might have been +4.5 and -7.5. If the polarity matters, I'll give it another test. But the crucial problem was that it didn't split evenly.

 

[lazeerer]

My board splits it perfect at 6.3v each which is his Original PCB .

Input Voltage is From a Walwart at 12.6v "Iam Rounding ever so slightly. Numbers are Pretty much on the money though."


Also Please note i do not have my fixed 5V LDO regulator hooked up to the Board because the panel i am using can take the Higher Voltage and its not needed.

IF its need I can Hook it up to test it separately but iam pretty sure when i had it hooked up when i was using the other panel that i think you are using now it worked Fine.


Edit:

Are you measuring before the Fixed 5V regulator.?

 

[rhd]

Edit:

Are you measuring before the Fixed 5V regulator.?

No, I'm measuring the OPH+ and OPH- output, relative to OPH_GND

The fixed 5V regulator shouldn't interact with Jib's circuit. My LED panel has 4 leads. It has a 5V+ and GND that it uses for power, and they're separate from the two leads that it actually measures voltage on.

When I measured the 4.5V and -7.5V, I didn't even have the LED panel connected yet, I was just testing the circuit's output (before daring to connect an Ophir). I measured those two values using two DMMs. One was OPH_GND to OPH+, the other was OPH_GND to OPH-.

 

[lazeerer]

When I messure OPH_GND to OPH+


I Get ..........6.27V


Then when i Measure OPH_GND to OPH-

I Get..........-6.24v


You sure you have it hooked up together correctly.?

I have a picture of how Mine is hooked up minus the Fixed 5V regulator since iam using a different panel right now then the original one i was going to use that you are using now:

 

[rhd]

When I messure OPH_GND to OPH+


I Get ..........6.27V


Then when i Measure OPH_GND to OPH-

I Get..........-6.24v


You sure you have it hooked up together correctly.?

I have a picture of how Mine is hooked up minus the Fixed 5V regulator since iam using a different panel right now then the original one i was going to use that you are using now:
http://i944.photobucket.com/albums/ad289/Laseerer/A A New/DualRailHookup.png

I'm fairly certain that I didn't make any casual errors in hooking it up. I've got a second set of parts on order from digikey, so I'll try again.

The two transistors that I used were manufactured by different companies, and looked fairly different physically from each other. I don't know how specifically those parts need to be BD437 and BD438s, but if someone had a pin compatible alternative NPN and PNP set of transistors to suggest (from digikey), I'd give that a shot. I have 7 more PCBs to play around with.

EDIT: To clarify, digikey only had one option each for the BD437 and 438 - and they were from different manufacturers.

 

[lazeerer]

Figured that already but never know. Ive over looked the stuff that has been right in my face looking at me before so i figure better to ask then not..

Iam Almost certain He gets his parts from mousers. Have you tried there.

 

[rhd]

Figured that already but never know. Ive over looked the stuff that has been right in my face looking at me before so i figure better to ask then not..

Iam Almost certain He gets his parts from mousers. Have you tried there.

I dislike Mouser for orders into Canada. Shipping costs $20 instead of $8 (from DigiKey), and it takes 4 days, instead of overnight (from DigiKey)

Is anyone familiar enough with the BD437/438 to either:

1) Confirm that my part selections were OK
2) Suggest alternate / equivalents from Digikey?

I've been using:
Digi-Key - 497-7171-5-ND (Manufacturer - BD437)
Digi-Key - BD438STU-ND (Manufacturer - BD438STU)