Hi,
I have a basic setup of a 5" LCD TV, a video transmitter and a
receiver. Each piece of equipment is powered by 3 12v batteries which
are each wired to 3 seperate switches, allowing me to turn the power
on and off from one location.

However, I wondered if I could replace these 3 switches with just one
switch, allowing me to power all 3 devices by just the one switch.

Is this possible?

Regards,

Sean

sean wrote:
>
> Hi,
> I have a basic setup of a 5" LCD TV, a video transmitter and a
> receiver. Each piece of equipment is powered by 3 12v batteries which
> are each wired to 3 seperate switches, allowing me to turn the power
> on and off from one location.
>
> However, I wondered if I could replace these 3 switches with just one
> switch, allowing me to power all 3 devices by just the one switch.

As long as you choose a switch with a
high enough current rating to handle all
three, it should work...

sean wrote:

> Hi,
> I have a basic setup of a 5" LCD TV, a video transmitter and a
> receiver. Each piece of equipment is powered by 3 12v batteries which
> are each wired to 3 seperate switches, allowing me to turn the power
> on and off from one location.
>
> However, I wondered if I could replace these 3 switches with just one
> switch, allowing me to power all 3 devices by just the one switch.
>
> Is this possible?
>
> Regards,
>
> Sean
I'm not saying you won't run into problems by doing so how ever,
in theory that should work as long as the switch and single battery
you select will handle the load.
There is a remote possibility how ever, that one of the devices could
be using a raised common from the (-) rail for example, to derive a -
offset/bipolar source from the assumed non-shared supply.


--
"I'd rather have a bottle in front of me than a frontal lobotomy"

"Daily Thought:

If I only enough steam to create a thought"

http://webpages.charter.net/jamie_5"

Tom2000 wrote:
> I'm helping a guy with a microcontroller project.
>
> He's going to use some BCD thumbwheels to set a time delay. He
> purchased some at a local surplus store for a buck each. But they
> were 9's complement thumbwheels, not standard decimal-coded switches.
>
> I'd never heard of 9's complement switches before, but from the truth
> table he sent me, I found that decoding them was no problem. (See
> below)
>
> My question is this: what sort of equipment might have used these
> switches, and what generation? I read about that system (and
> complement arithmetic in general) on Wikipedia and surmise that they
> might have fed a decimal adder, or somehting like that.
>
> Has anyone ever encountered these, and on what sort of equipment?
> What were they used for?
>
-- snip --
>

Something like this would be of use if you were preloading an up-counter
like, IIRC, a 7490 or 74190. You load the counter, then count up until
you get a 'carry' output (at 99...99), and voila!, you've counted out
the number on the switches.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html

On Mon, 11 Feb 2008 10:26:47 -0800, Tim Wescott <tim@seemywebsite.com>
wrote:

>
>Something like this would be of use if you were preloading an up-counter
>like, IIRC, a 7490 or 74190. You load the counter, then count up until
>you get a 'carry' output (at 99...99), and voila!, you've counted out
>the number on the switches.

Thanks, Tim. That makes sense.

Tom

In article <hbvvq35nqm236q81g27lr10bat1hjeu7jk@4ax.com>,
Tom2000 <abuse@giganews.net> wrote:
>
>I'm helping a guy with a microcontroller project.
>
>He's going to use some BCD thumbwheels to set a time delay. He
>purchased some at a local surplus store for a buck each. But they
>were 9's complement thumbwheels, not standard decimal-coded switches.
>
>I'd never heard of 9's complement switches before, but from the truth
>table he sent me, I found that decoding them was no problem. (See
>below)
>
>My question is this: what sort of equipment might have used these
>switches, and what generation? I read about that system (and
>complement arithmetic in general) on Wikipedia and surmise that they
>might have fed a decimal adder, or somehting like that.
>
>Has anyone ever encountered these, and on what sort of equipment?
>What were they used for?

Digging out a Fairchild TTL Applications handbook from 1973, they
show they could be used with the 9310 decimal counters for multistage
programmable counters. (When Texas Instruments did their version they
numbered it the 74160). The 74160-63 family are synchronous up counters
with preset inputs. There is logic in the chip to feed the clock control
inputs of the next counter in a chain. All chips in the chain get the
clock pulse in parallel, with a couple of clock control inputs that
enable the count, or load from the inputs.

The trick for using a 9's complement input value is that there's an
extra Nand gate needed that decodes when the counter chain is at 9...98.
When that happens, instead of the counter going to 9...99, the counter
chain gets set to the value coming in from the switches. So the
count runs from the complement value up to the 9...98. Looks like it
might get a bit wierd if the switch setting is 0...00.

Mark Zenier mzenier@eskimo.com
Googleproofaddress(account:mzenier provider:eskimo domain:com)

On Tue, 12 Feb 2008 04:43:19 +0000, Mark Zenier wrote:

> In article <hbvvq35nqm236q81g27lr10bat1hjeu7jk@4ax.com>, Tom2000
> <abuse@giganews.net> wrote:
>>
>>I'm helping a guy with a microcontroller project.
>>
>>He's going to use some BCD thumbwheels to set a time delay. He
>>purchased some at a local surplus store for a buck each. But they were
>>9's complement thumbwheels, not standard decimal-coded switches.
>>
>>I'd never heard of 9's complement switches before, but from the truth
>>table he sent me, I found that decoding them was no problem. (See
>>below)
>>
>>My question is this: what sort of equipment might have used these
>>switches, and what generation? I read about that system (and complement
>>arithmetic in general) on Wikipedia and surmise that they might have fed
>>a decimal adder, or somehting like that.
>>
>>Has anyone ever encountered these, and on what sort of equipment? What
>>were they used for?
>
> Digging out a Fairchild TTL Applications handbook from 1973, they show
> they could be used with the 9310 decimal counters for multistage
> programmable counters. (When Texas Instruments did their version they
> numbered it the 74160). The 74160-63 family are synchronous up counters
> with preset inputs. There is logic in the chip to feed the clock
> control inputs of the next counter in a chain. All chips in the chain
> get the clock pulse in parallel, with a couple of clock control inputs
> that enable the count, or load from the inputs.
>
> The trick for using a 9's complement input value is that there's an
> extra Nand gate needed that decodes when the counter chain is at 9...98.
> When that happens, instead of the counter going to 9...99, the counter
> chain gets set to the value coming in from the switches. So the count
> runs from the complement value up to the 9...98. Looks like it might
> get a bit wierd if the switch setting is 0...00.
>
> Mark Zenier mzenier@eskimo.com
> Googleproofaddress(account:mzenier provider:eskimo domain:com)

For most things (certainly if it were used in a frequency synthesizer)
the first few "digits" would be fixed, with only trailing digits being
adjustable. That would take care of the '000' case.

--
Tim Wescott
Control systems and communications consulting
http://www.wescottdesign.com

Need to learn how to apply control theory in your embedded system?
"Applied Control Theory for Embedded Systems" by Tim Wescott
Elsevier/Newnes, http://www.wescottdesign.com/actfes/actfes.html

On Tue, 12 Feb 2008 04:43:19 GMT, mzenier@eskimo.com (Mark Zenier)
wrote:

>Digging out a Fairchild TTL Applications handbook from 1973, they
>show they could be used with the 9310 decimal counters for multistage
>programmable counters. (When Texas Instruments did their version they
>numbered it the 74160). The 74160-63 family are synchronous up counters
>with preset inputs. There is logic in the chip to feed the clock control
>inputs of the next counter in a chain. All chips in the chain get the
>clock pulse in parallel, with a couple of clock control inputs that
>enable the count, or load from the inputs.
>
>The trick for using a 9's complement input value is that there's an
>extra Nand gate needed that decodes when the counter chain is at 9...98.
>When that happens, instead of the counter going to 9...99, the counter
>chain gets set to the value coming in from the switches. So the
>count runs from the complement value up to the 9...98. Looks like it
>might get a bit wierd if the switch setting is 0...00.
>

Thanks very much, Mark, for the time you spent researching this. And
I'm amazed that you still have 1973 data books on the shelf! (Amazed
in a jealous sort of way. I wish I'd kept a lot of stuff from that
era.)

That's sort of the circuitry I was expecting after I'd read that Wiki
article.

Best,

Tom