BS2 Light Dimmer
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[font=arial,helvetica]Anyone have any thoughts on a simple BS2 light dimmer circuit?
I have need of a circuit to completely control brightness (0-100%) of about
300 watts of incandescent lamps in special timing sequences. ·To date I have
used a BS1 to simply turn on and off the Slow ON/OFF Velleman Dimmer kits
sold by Jameco. ·This works very nicely but since I will need to run multiple
sets of 300 watts each, the Velleman kit approach gets expensive AND is hard
to adjust the dim timing to be the same for all units.
I also tried using a BS2 xmitting X-10 commands. ·This would have been a nice
solution (multiple X-10 units responding) but it turns out the dimming,
especially at lower levels, is not smooth enough. ·(Can see the notching.)
The x-10 folks suggested the newer (more expensive) units but they also show
incremental dimming when driven by the BS2 commands.
It seems to me there ought to be a simple approach to driving an inexpensive
TRIAC circuit. ·If the BS2 is fast enough, I would suspect the zero crossing
of the AC line could be detected and the firing time to the TRIAC gate varied
to provide a smooth dimming.
Anybody have thoughts on the TRIAC approach, or any other simple, inexpensive
circuits
Fred Miller
tractionfan@aol.com
http://hometown.aol.com/tractionfan[/font]
I have need of a circuit to completely control brightness (0-100%) of about
300 watts of incandescent lamps in special timing sequences. ·To date I have
used a BS1 to simply turn on and off the Slow ON/OFF Velleman Dimmer kits
sold by Jameco. ·This works very nicely but since I will need to run multiple
sets of 300 watts each, the Velleman kit approach gets expensive AND is hard
to adjust the dim timing to be the same for all units.
I also tried using a BS2 xmitting X-10 commands. ·This would have been a nice
solution (multiple X-10 units responding) but it turns out the dimming,
especially at lower levels, is not smooth enough. ·(Can see the notching.)
The x-10 folks suggested the newer (more expensive) units but they also show
incremental dimming when driven by the BS2 commands.
It seems to me there ought to be a simple approach to driving an inexpensive
TRIAC circuit. ·If the BS2 is fast enough, I would suspect the zero crossing
of the AC line could be detected and the firing time to the TRIAC gate varied
to provide a smooth dimming.
Anybody have thoughts on the TRIAC approach, or any other simple, inexpensive
circuits
Fred Miller
tractionfan@aol.com
http://hometown.aol.com/tractionfan[/font]
Comments
I have a design completed that controls AC lighting from very small loads up to 100's of amps on single-phase or 3-phase lines with hundreds of steps of dimming, as opposed to x-10's 17 steps. I did my early prototyping with a BS2. What I can say is forget about using the Stamp for zero-cross detection or the gate firing if you want to get anywhere near 100% out. There's a PIC Ap-note on this that shows a triac being fired with very fine incremental steps by a very simple circuit with an inexpensive PIC - but I know of·a very experienced group of engineers who spent a small fortune trying to prove out the AN method, and line noise kept destroying the PICs despite the snubbers and varistors they added. It may work well at 120V and may be the closest thing to the 'simple' idea you are looking for. The circuit·I have now has a PIC 18xx at the heart of it- forget about basic or even C. The PIC, or an external Stamp can be programmed to command any variety of phase angles (lighting levels) as needed. This was the result of a very costly development project, so I'd ask that you contact me off-list IF you feel that your project will·still justify the·effort.
chris@tampabay.rr.com
Original Message
From: tractionfan@aol.com [noparse][[/noparse]mailto:tractionfan@aol.com]
Sent: Wednesday, February 28, 2001 1:10 PM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Re: BS2 Light Dimmer
[font=arial,helvetica]Anyone have any thoughts on a simple BS2 light dimmer circuit?
I have need of a circuit to completely control brightness (0-100%) of about
300 watts of incandescent lamps in special timing sequences. ·To date I have
used a BS1 to simply turn on and off the Slow ON/OFF Velleman Dimmer kits
sold by Jameco. ·This works very nicely but since I will need to run multiple
sets of 300 watts each, the Velleman kit approach gets expensive AND is hard
to adjust the dim timing to be the same for all units.
I also tried using a BS2 xmitting X-10 commands. ·This would have been a nice
solution (multiple X-10 units responding) but it turns out the dimming,
especially at lower levels, is not smooth enough. ·(Can see the notching.) ·
The x-10 folks suggested the newer (more expensive) units but they also show
incremental dimming when driven by the BS2 commands.
It seems to me there ought to be a simple approach to driving an inexpensive
TRIAC circuit. ·If the BS2 is fast enough, I would suspect the zero crossing
of the AC line could be detected and the firing time to the TRIAC gate varied
to provide a smooth dimming.
Anybody have thoughts on the TRIAC approach, or any other simple, inexpensive
circuits
Fred Miller
tractionfan@aol.com
http://hometown.aol.com/tractionfan
Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
[/font]
controlled by a 0-10 volt (2.25 ma @12v)DC voltage.
With a DAC you can get very fine control. The units
will handle 380 Watts at 110 volts. I have had one
running 24/7 for over a year with no problems. Unit
is not too cheap - $22 , but works great!
Lew Muller
lew@s...
--- tractionfan@a... wrote:
> Anyone have any thoughts on a simple BS2 light
> dimmer circuit?
>
> I have need of a circuit to completely control
> brightness (0-100%) of about
> 300 watts of incandescent lamps in special timing
> sequences. To date I have
> used a BS1 to simply turn on and off the Slow ON/OFF
> Velleman Dimmer kits
> sold by Jameco. This works very nicely but since I
> will need to run multiple
> sets of 300 watts each, the Velleman kit approach
> gets expensive AND is hard
> to adjust the dim timing to be the same for all
> units.
>
> I also tried using a BS2 xmitting X-10 commands.
> This would have been a nice
> solution (multiple X-10 units responding) but it
> turns out the dimming,
> especially at lower levels, is not smooth enough.
> (Can see the notching.)
> The x-10 folks suggested the newer (more expensive)
> units but they also show
> incremental dimming when driven by the BS2 commands.
>
> It seems to me there ought to be a simple approach
> to driving an inexpensive
> TRIAC circuit. If the BS2 is fast enough, I would
> suspect the zero crossing
> of the AC line could be detected and the firing time
> to the TRIAC gate varied
> to provide a smooth dimming.
>
> Anybody have thoughts on the TRIAC approach, or any
> other simple, inexpensive
> circuits
>
> Fred Miller
> tractionfan@a...
> http://hometown.aol.com/tractionfan
>
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[font=arial,helvetica]Anyone have any thoughts on a simple BS2 light dimmer circuit?
to adjust the dim timing to be the same for all units.
Anybody have thoughts on the TRIAC approach, or any other simple, inexpensive
circuits [/font]
[font=arial,helvetica][/font]
[font=arial,helvetica]I have used a old circuit cobbled together from many sources that uses an ancient UJT to drive a triac at zero crossing. The crossing is detected with a transistor pair and the dimming level can be optically isolated from the triac circuit. A unity gain opamp drives the optoisolator. The whole circuit is line powered through a 1uf capacitor. It is reliable but may require some tinkering. I don't have a PCB for it since the original circuit has·undergone so many modifications that they are all "one offs". Using a string of digital pots to drive the UGF opamps would be a way of achieving a specific dim rate in unison for several units but I have not tried it. [/font]
[font=arial,helvetica]In sum, It is old tech but dirt cheap and once coaxed into operation, highly reliable. I have had units interfaced with occupancy sensors controlling lights around the house for 10 years without failure. [/font]
[font=arial,helvetica]Contact me off list if you are interested. [/font]
[font=arial,helvetica]seangib@home.com [/font]