Today's Message Index:
----------------------
1. 07:05 AM - Re: Re: Dimmers driving displays... (C&K)
2. 08:07 AM - Re: Re: Dimmers driving displays... (Robert L. Nuckolls, III)
3. 12:32 PM - Re: Dimmers driving displays... (andymeyer)
4. 01:00 PM - Re: Re: Dimmers driving displays... (C&K)
Message 1
| INDEX | Back to Main INDEX |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Dimmers driving displays... |
Innovative and ubiquitous parts for sure.
If 150 mA output is enough, a LM723 would do it without any transistors.
Ken
On 07/04/2015 12:19 PM, Robert L. Nuckolls, III wrote:
> I spend a lot of time on the road these days . . . useful for
> what I call "asphalt design time". Here's yet another option for
> slaying Andy's dimming dragon . . .
>
> Few pieces of silicon have enjoyed so long and rich a history
> in electronics as the 555 timer. I remember seeing the data
> sheets on this device from Signetics . . . a sales
> rep dropped it off with several others at my first TC aviation
> design job at Electro-Mech about 1975 . . .
>
> I won't go into details of its features here but suffice it to
> say that this device might fit into yet one more application that
> Mr. Camenzind probably never imagined.
>
> http://tinyurl.com/yb23fes
>
> <http://tinyurl.com/yb23fes>In the schematic below, we see how the
> 555's two comparators
> biased at 1/3 and 2/3 of supply voltage can be used to provide
> functional logic that goes to the task at hand.
>
> Emacs!
>
> Wired as shown, dimmer output voltage sample is applied
> to the two comparators on pins 2 and 6. If the dimmer
> output goes lower than 4v, pin 3 goes HI and turns
> the two transistors ON thus applying full bus voltage
> to the two instruments needing special attention. If the
> dimmer output is cranked up to more than 8 volts, the
> 555 output goes LO and turns both transistors off. Under
> this condition, dimmer output has control over the
> displays on the two instruments. It remains in this
> condition until dimmer output is dialed down below 4
> volts whereupon, the 555 'flips' to the daytime
> lighting condition.
>
> This circuit could be spider-webbed into the back
> shell of a D-sub connector . . . not unlike the
> relay packaging project we discussed here on the List
> last week.
>
>
> Bob . . .
>
Message 2
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Dimmers driving displays... |
At 09:01 2015-04-08, you wrote:
>
>Innovative and ubiquitous parts for sure.
>If 150 mA output is enough, a LM723 would do it without any transistors.
>Ken
That one doesn't 'pop out' at me. Can you share
a sketch?
Bob . . .
Message 3
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Dimmers driving displays... |
Can something as simple as this be done... The diode in your circuit got me thinking.
If the output of the inverter is high impedance when it's output is low, the voltage
from the dimmer would cross the diode (with a diode drop - not a problem
- just calibrate the brightness accordingly.) When the voltage on the dimmer
dropped low enough that the inverter went to high output, the diode would block
that voltage from the "dimmed power to other appliances" yet apply that voltage
to the CGR-30P and Aerospace Logic...
It's been too long since circuits class - way too long.
I appreciate the input and thoughts!
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=440464#440464
Attachments:
http://forums.matronics.com//files/untitled_165.png
Message 4
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Dimmers driving displays... |
On 08/04/2015 11:04 AM, Robert L. Nuckolls, III wrote:
> <nuckolls.bob@aeroelectric.com>
>
> At 09:01 2015-04-08, you wrote:
>>
>> Innovative and ubiquitous parts for sure.
>> If 150 mA output is enough, a LM723 would do it without any transistors.
>> Ken
>
> That one doesn't 'pop out' at me. Can you share
> a sketch?
>
>
> Bob . . .
>
A sketch you say...
The LM723 is an older but versatile voltage regulator (currently $0.75
from digi-key).
The 14 pin DIP has a 7 volt reference, a comparator, and a 150 mA
capable transistor in it. All good things for this type of circuit.
However sketching it out reminds me that its output is a NPN transistor
so the diode and 2N3906 from your 555 sketch would still be necessary
which negates any meaningful parts reduction. Also forgot that it has a
5volt differential comparator input limitation that complicates things
just enough for me to loose interest in using it for this application.
The equivalent circuit on page 2 of the Texas Instruments data sheet
illustrates the part nicely.
http://www.ti.com/lit/ds/symlink/lm723.pdf
I have used this part for outdoor equipment which is why it came to
mind. I'll likely use another one on a Briggs lawn tractor that has no
regulation. The tractor is half wave DC and only rated at 3 amps but it
ramps up to at least 17 volts and tends to kill batteries. Several of
the discrete parts in the example circuits such as C1 and R3 are not
usually required. Since it can tolerate 40 volts, it doesn not really
need any input power conditioning. The current sense resistor (Rsc) and
connections to the Current Sense (CS) or limit (CL) pins are not
required. The plastic DIP version only has commercial temperature
ratings but it has worked fine for me for many years winter and summer
on outside equipment.
Ken
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|