El-cheapo incand light goes regulated

I thought that i'd also share this one with you.

First, take El-cheapo flashlight.


Then take one previously assebled boost-converter/regulator.


Attach it to the lamp assembly.


Assemble the torch and hit the switch.


Actually it wasn't so easy. First of all, the contacts on the bloody lamp can't be soldered. So I had to make other arrangements to connect the wiring. Secondly I made this light in about one hour mainly because the boost-converter was previously assembled to evaluate it before starting 2D mag++ project. Next I had to solve the heating problem, since this light didn't have any heatsink to the bulb. Well I didn't solve it, just ignored it. This lamp actually isn't so cheaply manufactured I made it sound. The reflector took quite a punishment from a 12V/8.4W bulb with no visible damage. Of course I didn't drive it too long, but some 15 minutes at least. This one is built to be a economic thrower, not general lighting for long periods of time. It does it fairly well.

The bulb is once again Magnum Star Xe 6-cell driven about 7.25-7.30 volts. I wouldn't dream of putting anything more powerful in to this light. Power is drain from 4 D size NiMh cells, rated 4.5 Ah. They were about half used and remained at 4.3 volts total with full load (about 1.5-1.6A). I consider this as a fair result, since they were quite cheap. I measured this converters efficiency to be 89% (in: 4.00V/1.75A out:7.28V/0.86A) so the lamp should be running a decent time with fully charged cells. On the other hand, it can be driven with alkalines, but I'd say that they won't last very long with these discharge currents.

Funny thing about this light is, that it's actually better sealed than a maglite, so I'll consider it weather-proof.

So much for the 6D+ performance in a cheap 4D light. Cheers.

Hieno homma - taisit kymmenkertaistaa lampun arvon?


... and the same in english: Great job - I guess that you multiplied the value of the flashlight by a factor of 10?

-N

Now that you mention it.

light itself, 7.5€ (Wasn't the cheapest around, but I liked it.)
converter parts, about 17€ (excluding epoxy, wires, etc.)
NiMH cells, 8€
bulb, 4.9€
+cost of delivery (four different suppliers), let's say 4*5€.
+charger
+time (&lost sleep)
+sanity
...

So if you include in your calcculations charger, time or sanity, cost of the light was multiplied approximately by 10. Don't know about the value on the other hand. (I's valuable to me atleast!)

Hi nimhpwr

Nice work!!!

And welcome to CPF :wave:

Welcome nimhpwr!

Mind posting the schematic for your converter? There is a need for more incan regulators, and they all don't necessarily need to be miniaturized like the previous PWM LVR in the A2 and winny's PIR, or AWR's linear Hotdriver.

Nice work nimhpwr, A diagram of the schematics would be nice!

Do you know if winny's regulator has been de-bugged? I know that there was an issue with programing.


Thanks, Gammaray

bfg9000 said:

Welcome nimhpwr!

Mind posting the schematic for your converter? There is a need for more incan regulators, and they all don't necessarily need to be miniaturized like the previous PWM LVR in the A2 and winny's PIR, or AWR's linear Hotdriver.

Click to expand...

Circuit is based on National Semiconductors LM2577T-ADJ, and the schematics can be found in its datasheet. Its the very first example diagram in there (page 3). I also made a spreadsheet to calculate/evaluate appropriate component/electrical values. It's based on datasheet, so all the formulas can be found there.

Might be a good idea not to blindly trust to my entagled sheet.

Simple switcher series produces simple regulators but the downside is that it can't drive much more powerful bulbs with so low Vin. It should be able to drive 12V/20W from 9 NiMh cells, as long as cell voltage don't go under 1.1V. Maby would work better if one used 10 cells, but startup with fully charged hot cells would be vith over 12V. But with little brainwork I believe the circuit can be pushed there (but not much over). You will be overdriving the poor bulb anyway, so no problem there.:devil: Offcourse if you should take 20W from just 4 cells it would mean over 4A discharge. Bye bye run-time...

Notes:
*Inductor is "just a coil", bought from same shop as the IC. Works quite well with anything reasonable. (It was be rated 100uH/7A, if I remember correctly. Or was it 5A...)
*R2 is 2kohm and R1 is 20k variable trimmer. This gives output from V_in to about 13.5V
*Rc is 1kohm and Cc is 3.3uF
*I changed the diode to 90SQ045 for lower Vf (mesured 0.317V, datasheet says 0.45V)
*The IC itself didn't got even warm when no heatsink was present. Don't blame me if you fry your regulator/torch/house/etc. I didn't have the patience to wait for long it to get warm. It's driven without any heatsink in my 2D mag++ has worked without any problems (so far).
*Sheet takes Vin, Vout, Iout, efficiency, battery capacity, inductance, dides Vf, Rc, Cout and Cc as parameters and calculates limits to these components based on datasheet. Battery capacity is just to evaluate approximate run time. The sheet also shows how far you are from boundary-value (%).