Vistalite Dimmer Switch

hippy said:

Spotted this dimmer switch on Phantom: phantom-phantom-Open ↗
cycles.com.au/Content.asp?S=Details%20@ID=1553

What would be needed to make your own and how much do you
reckon it would cost?

It'd make my 15w globes a bit more useful but I don't
wanna pay $70 for it.

Supposedly[1] you can make a dimmer from 2 x LM311 1 x
MTP3055E 1 heat sink for above 4 Resistors 2 x 10K, 1 x 22K
& 1 x 220K 1 Pot 20K-50K 2 signal diodes 1 x 330pF Cap piece
of vero board

1 double matchbox size box (optional)

[1]A mate turned up with it. Firstly for help to lay it
out on the vero board, then for help to get his
soldered creation working. We ended up stripping
everything off the board and trying to get it working
on a protype board.

Lets just say after him telling me that he let the magic
smoke out of the 50K pot (boogle), I wasn't surprised when
nothing worked on the protype board.

It basically is a oscillator that feeds a PWM that pulses
the MTP to turn the light on and off. The pot varies the
duty cycle. He says he has seen one working and the the freq
is 800Hz, but basic RC calcs say 13KHz and simple circuit
analysis says about 20KHz. Unfortunately, neither of us has
a scope to see this.

At this stage, I think he has an incorrect circuit diagram
an I can not find any similar circuit. If anyone knows of an
op-amp oscillator circuit that ties the output to both the
inverting and non-inverting inputs with diodes, then I would
like to see it.

End story, if I get something working, then I will post
a circuit.

hippy wrote:
Spotted this dimmer switch on Phantom:
http://www.phantomcycles.com.au/Content.asp?S=Details%20@ID=1553

These things don't work very well, as incandescent globes are not efficient when run under their intended power. The following table for a 2W globe, shamelessly stolen from http://www.cs.indiana.edu/~willie/lvr.html says it all:

Power Efficiency
2.38 1.23
2.06 1.00
1.76 0.89
1.48 0.65
1.23 0.52
0.98 0.35
0.76 0.21
0.55 0.09

The long and the short of it is that if you put in 1/2 the power, you get out 1/3rd the light, which is pretty crappy. Much better to buy a 5W globe instead.

On a similar topic, I'm currently playing with a set of Lithium Ion batteries from a notebook that I had kicking around. These are awesome energy density compared to NiCd or NiMH. I've built a 7.4V 8.9Ah pack up with them that weighs a scant 350g. To put it in perspective, the 2Ah 6V NiCd pack I bought with my 5W Vistalight weight about 300g. That's about 4 times as much bang for the same weight.

Now I just need to build a charger to charge it, and a regulator for the bulb. Knew that engineering degree would come in useful eventually 🙂

Regards,

Suzy

hippy said:

Spotted this dimmer switch on Phantom: phantom-phantom-Open ↗
cycles.com.au/Content.asp?S=Details%20@ID=1553

What would be needed to make your own and how much do you
reckon it would cost?

It'd make my 15w globes a bit more useful but I don't
wanna pay $70 for it.

hippy

--

I use lithium ion batteries on my vista lights and since the
voltage is
8.4 when fresh I use a simple 555 timer and mosfet switch
circuit as a dimmer. I only have two positions 70 % power
and full power. I don't like having pots (variable
dimming) in circuits as the are susepible (fail alot)
(cant spell) to damage and water. I have modified another
circuit that keeps a constant voltage to the lamp even
when the battery voltage changes as it discharges. This
also uses a 555 timer. Here is a link to the dse pages
showing an example circuit.

dse.com.aucgiOpen ↗
bin/dse.filereader?409979c1011a61ba2741c0a87f9c0724+EN/cata-
logs/DTS0000054

The cost for parts excluding a box would be under $10.00.

Even though the circuit shows 12 volts it should work fine
from 6 or 7.2 depending on your vistalight system.

The main problem with dimmers an halogen lights is that when
an halogen is run at less power it becomes less efficient.
So if you drop the power by half you will get less than half
the amount of light. On the plus side it makes the lamps
last a really long time. People have run lamps under voltage
constantly for tens of years. Of course you could see better
with a candle.

Mail me if you won't more detal. remove pants to reply.

"Terry Collins" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

hippy said:

Spotted this dimmer switch on Phantom: phant-phant-Open ↗
omcycles.com.au/Content.asp?S=Details%20@ID=1553

What would be needed to make your own and how much do
you reckon it would cost?

It'd make my 15w globes a bit more useful but I don't
wanna pay $70 for it.

Supposedly[1] you can make a dimmer from 2 x LM311 1 x
MTP3055E 1 heat sink for above 4 Resistors 2 x 10K, 1 x
22K & 1 x 220K 1 Pot 20K-50K 2 signal diodes 1 x 330pF Cap
piece of vero board

1 double matchbox size box (optional)

[1]A mate turned up with it. Firstly for help to lay it
out on the vero board, then for help to get his
soldered creation working. We ended up stripping
everything off the board and trying to get it working
on a protype board.

Lets just say after him telling me that he let the magic
smoke out of the 50K pot (boogle), I wasn't surprised when
nothing worked on the protype board.

It basically is a oscillator that feeds a PWM that pulses
the MTP to turn the light on and off. The pot varies the
duty cycle. He says he has seen one working and the the
freq is 800Hz, but basic RC calcs say 13KHz and simple
circuit analysis says about 20KHz. Unfortunately, neither
of us has a scope to see this.

At this stage, I think he has an incorrect circuit diagram
an I can not find any similar circuit. If anyone knows of
an op-amp oscillator circuit that ties the output to both
the inverting and non-inverting inputs with diodes, then I
would like to see it.

End story, if I get something working, then I will post a
circuit.

There's a simple circuit for an oscillator here, on page 12.
You might need to fiddle a few components to get the right
frequency. national.comLM111.pdfOpen ↗

Marty

agamlen wrote:

...snip....

Quoted message said:

dse.com.aucgiOpen ↗
bin/dse.filereader?409979c1011a61ba2741c0a87f9c0724+EN/ca-
talogs/DTS0000054

Thanks. I have something similar to this that I am playing
around with.

Marty Wallace said:

There's a simple circuit for an oscillator here, on page
12. You might need to fiddle a few components to get the
right frequency. national.comLM111.pdfOpen ↗

Thanks. We already have that as an alternative. Involves a
few more pieces that his circuit, but if the 555 circuits
doesn't suffice, I will modify their suggested app circuit.

hippy said:

Spotted this dimmer switch on Phantom: phantom-phantom-Open ↗
cycles.com.au/Content.asp?S=Details%20@ID=1553

What would be needed to make your own and how much do you
reckon it would cost?

It'd make my 15w globes a bit more useful but I don't
wanna pay $70 for it.

lightbrain.8m.comlightbrain.8m.comOpen ↗

"hippy" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

Spotted this dimmer switch on Phantom: phantom-phantom-Open ↗
cycles.com.au/Content.asp?S=Details%20@ID=1553

What would be needed to make your own and how much do you
reckon it would cost?

It'd make my 15w globes a bit more useful but I don't
wanna pay $70 for it.

hippy

Hip,

You mentioned a while ago that you might have a spare set of
old V brakes laying around......maybe we could do some sort
of a deal and I could make you up a dimmer to whatever specs
you want????

Let me know,

Gags