Rotary switch?

G

George

Guest
The old Radio Shack catalog had two rotary switches. One was a
12-pole, 1-position, shorting. The other was a 2-pole, 6 position,
non-shorting. The second one is the only one left now:

http://www.radioshack.com/product/index.jsp?productId=2062536

I don't understand the lingo. Can someone point me to schematic
symbols for these two switches, or an explanation of what they do?
And what is the "shorting" thing all about.

More generally, I'm making an intervalometer for my camera, and in
order to change the period between pictures, I need to vary one of
the 555 timer resistors. And I thought a multi-position switch of
some kind, with individual resistors, might work better than a
pot. But I also need an on/off switch for the whole thing. Can the
R/S rotary switch be rigged to do both functions?

Thanks for any help.
 
On Sun, 31 Oct 2010 08:26:00 -0500, George <gh424NO824SPAM@cox.net>
wrote:

The old Radio Shack catalog had two rotary switches. One was a
12-pole, 1-position, shorting. The other was a 2-pole, 6 position,
non-shorting. The second one is the only one left now:

http://www.radioshack.com/product/index.jsp?productId=2062536

I don't understand the lingo. Can someone point me to schematic
symbols for these two switches, or an explanation of what they do?
And what is the "shorting" thing all about.

More generally, I'm making an intervalometer for my camera, and in
order to change the period between pictures, I need to vary one of
the 555 timer resistors. And I thought a multi-position switch of
some kind, with individual resistors, might work better than a
pot. But I also need an on/off switch for the whole thing. Can the
R/S rotary switch be rigged to do both functions?

Thanks for any help.
Click to expand...
The "one position," or one pole, switches a single entity between one of
twelve other entities (either side could be the input or output).
"Shorting" is a "make before break" type, where in the transition
between positions there will be a spot where two of the 12-side entities
are connected, or "shorted," together and both of them are connected to
the main pole.

The two pole, six position switch connects each of the two poles
individually to one of six other contacts. "Non-shorting" is "break
before make," where in the transition between positions there will be a
spot where none of the 6-side entities are connected to the
corresponding main pole.

--
Rich Webb Norfolk, VA
 
George wrote:
The old Radio Shack catalog had two rotary switches. One was a
12-pole, 1-position, shorting. The other was a 2-pole, 6 position,
non-shorting. The second one is the only one left now:

http://www.radioshack.com/product/index.jsp?productId=2062536

I don't understand the lingo. Can someone point me to schematic
symbols for these two switches, or an explanation of what they do?
And what is the "shorting" thing all about.

More generally, I'm making an intervalometer for my camera, and in
order to change the period between pictures, I need to vary one of
the 555 timer resistors. And I thought a multi-position switch of
some kind, with individual resistors, might work better than a
pot. But I also need an on/off switch for the whole thing. Can the
R/S rotary switch be rigged to do both functions?

Thanks for any help.

I think you would do better using a pot. Radio shaft used to sell a
Click to expand...
add on switch that you can put on the pots they sell, you simply remove
the cover to the pot and replace it with this switch..


AS far as the shorting term goes, it just signifies that the leaving
contact and approaching contact will be joined as you change selection.
This will work fine if you are making a R latter, I don't know about
other functions how ever..
 
George wrote:
The old Radio Shack catalog had two rotary switches. One was a
12-pole, 1-position, shorting. The other was a 2-pole, 6 position,
non-shorting. The second one is the only one left now:

http://www.radioshack.com/product/index.jsp?productId=2062536

I don't understand the lingo. Can someone point me to schematic
symbols for these two switches, or an explanation of what they do?
And what is the "shorting" thing all about.

More generally, I'm making an intervalometer for my camera, and in
order to change the period between pictures, I need to vary one of
the 555 timer resistors. And I thought a multi-position switch of
some kind, with individual resistors, might work better than a
pot. But I also need an on/off switch for the whole thing. Can the
R/S rotary switch be rigged to do both functions?

Thanks for any help.
Click to expand...

Mouser Electronics still has 1,672 different rotary switches:

<http://www.mouser.com/Electromechanical/Switches/Rotary-Switches/_/N-5g2i/>


--
Politicians should only get paid if the budget is balanced, and there is
enough left over to pay them.
 
Jamie wrote:
George wrote:
The old Radio Shack catalog had two rotary switches. One was a
12-pole, 1-position, shorting. The other was a 2-pole, 6 position,
non-shorting. The second one is the only one left now:

http://www.radioshack.com/product/index.jsp?productId=2062536

I don't understand the lingo. Can someone point me to schematic
symbols for these two switches, or an explanation of what they do?
And what is the "shorting" thing all about.

More generally, I'm making an intervalometer for my camera, and in
order to change the period between pictures, I need to vary one of
the 555 timer resistors. And I thought a multi-position switch of
some kind, with individual resistors, might work better than a
pot. But I also need an on/off switch for the whole thing. Can the
R/S rotary switch be rigged to do both functions?

Thanks for any help.

I think you would do better using a pot. Radio shaft used to sell a
add on switch that you can put on the pots they sell, you simply remove
the cover to the pot and replace it with this switch..

AS far as the shorting term goes, it just signifies that the leaving
contact and approaching contact will be joined as you change selection.
This will work fine if you are making a R latter, I don't know about
Ladder
Click to expand...

other functions how ever..
Click to expand...

As usual, you don't know much of anything. That add on switch for a
pot was a power switch for a volume or tone control. What good does it
do to mention a part they haven't sold in years?


Also, you still can't pick the right words for your messages. Do you
still think an Electric microphone is a Crystal microphone?


--
Politicians should only get paid if the budget is balanced, and there is
enough left over to pay them.
 
On Sun, 31 Oct 2010 08:26:00 -0500, George <gh424NO824SPAM@cox.net>
wrote:

The old Radio Shack catalog had two rotary switches. One was a
12-pole, 1-position, shorting. The other was a 2-pole, 6 position,
non-shorting. The second one is the only one left now:

http://www.radioshack.com/product/index.jsp?productId=2062536

I don't understand the lingo. Can someone point me to schematic
symbols for these two switches, or an explanation of what they do?
And what is the "shorting" thing all about.
Click to expand...
What the switches do is to sequentially connect and disconnect one
moveable contact (the "common") from a series of fixed contacts (the
"contacts) as the switch's shaft is rotated.

"Shorting", or "make before break" means that before the switch common
leaves one contact it contacts the next, and "Non-Shorting", or "break
before make" means that the common leaves one contact before it
contacts the next

A "12-pole 1 position" switch is a misnomer, since all switches must
have at least two positions.

A 12-pole 2 position switch would be a switch with 12 commons and 12
contacts, where the commons would connect to, or disconnect from,
their respective contacts in unison.

A toggle switch equivalent would be a 12-pole single throw (12PST)
switch.

A 2-pole 6 position non-shorting switch would be one with 2 commons
and 6 contacts per common, where the commons would disconnect from one
contact before engaging the next.

Go to:

http://www.electro-nc.com/crl.cfm

Or Google "rotary switch" for more.

---

More generally, I'm making an intervalometer for my camera, and in
order to change the period between pictures, I need to vary one of
the 555 timer resistors. And I thought a multi-position switch of
some kind, with individual resistors, might work better than a
pot. But I also need an on/off switch for the whole thing. Can the
R/S rotary switch be rigged to do both functions?
Click to expand...
Yes.

If what you mean by "intervalometer" is an astable where you use the
output pulse to trigger the camera and the period between output
pulses to determine the frequency of the trigger pulses, then the
answer is "yes" if you use two 555's; one as an astable to generate
the time intervals and the other as a monostable to generate a
fixed-width trigger pulse for the camera, and they'd be wired like
this: (View in Courier)



.. 1 S1A C
..Vcc>------+--O<--O
.. | 2 |
.. +--O |
.. | 3 |
.. +--O |
.. | 4 |
.. +--O |
.. | 5 |
.. +--O |
.. 6 |
.. O |
.. |
.. |
.. |
.. +----------+-+-------+----------+----+-------+-------+
.. | |+ | | | | |
.. | [10ľF] | | | | [100K]
.. | | | | | | |
.. | GND | +---|----|-------|-------+
.. | | | | | | |
.. [R1] +---+---+ | | [Rt] +---+---+ |
.. | |_ Vcc_| | | | |_ Vcc _| |
.. +---------------O|D R|O-+ | +--O|D R|O--+
.. | 1 S1B | | | | | | |
.. +-[R2]-O<--O--+--|TH 7555| [10K] [Ct] |TH 7555| 100nF
.. | 2 | |__ | | | |_ | |
.. +-[R3]-O +-O|TR OUT|-[C2]-+----|--O|T OUT|---|-->TRIG
.. | 3 | | GND | 100nF | | GND | |
.. +-[R4]-O [Ct]+---+---+ | +---+---+ |
.. | 4 | | | | |
.. +-[R5]-O +------+---------------+-------+-------+
.. | 5 |
.. +-[R6]-O GND
.. 6
.. O

I've shown the circuit with CMOS 555s.

If you choose to use bipolars, connect a 100nF ceramic cap directly
across the Vcc and GND pins on each chip.

Do you need a circuit description?

You might be able to use a single 555, but for the extra buck or so,
I'd go with the fixed width trigger.

BTW, what are the intervals you're interested in?

---
JF
 
On Sun, 31 Oct 2010 11:02:50 -0500, John Fields
<jfields@austininstruments.com> wrote:

On Sun, 31 Oct 2010 08:26:00 -0500, George <gh424NO824SPAM@cox.net
wrote:

The old Radio Shack catalog had two rotary switches. One was a
12-pole, 1-position, shorting. The other was a 2-pole, 6 position,
non-shorting. The second one is the only one left now:

http://www.radioshack.com/product/index.jsp?productId=2062536

I don't understand the lingo. Can someone point me to schematic
symbols for these two switches, or an explanation of what they do?
And what is the "shorting" thing all about.

What the switches do is to sequentially connect and disconnect one
moveable contact (the "common") from a series of fixed contacts (the
"contacts) as the switch's shaft is rotated.

"Shorting", or "make before break" means that before the switch common
leaves one contact it contacts the next, and "Non-Shorting", or "break
before make" means that the common leaves one contact before it
contacts the next

A "12-pole 1 position" switch is a misnomer, since all switches must
have at least two positions.

A 12-pole 2 position switch would be a switch with 12 commons and 12
contacts, where the commons would connect to, or disconnect from,
their respective contacts in unison.

A toggle switch equivalent would be a 12-pole single throw (12PST)
switch.

A 2-pole 6 position non-shorting switch would be one with 2 commons
and 6 contacts per common, where the commons would disconnect from one
contact before engaging the next.

Go to:

http://www.electro-nc.com/crl.cfm

Or Google "rotary switch" for more.

---

More generally, I'm making an intervalometer for my camera, and in
order to change the period between pictures, I need to vary one of
the 555 timer resistors. And I thought a multi-position switch of
some kind, with individual resistors, might work better than a
pot. But I also need an on/off switch for the whole thing. Can the
R/S rotary switch be rigged to do both functions?

Yes.

If what you mean by "intervalometer" is an astable where you use the
output pulse to trigger the camera and the period between output
pulses to determine the frequency of the trigger pulses, then the
answer is "yes" if you use two 555's; one as an astable to generate
the time intervals and the other as a monostable to generate a
fixed-width trigger pulse for the camera, and they'd be wired like
this: (View in Courier)



. 1 S1A C
.Vcc>------+--O<--O
. | 2 |
. +--O |
. | 3 |
. +--O |
. | 4 |
. +--O |
. | 5 |
. +--O |
. 6 |
. O |
. |
. |
. |
. +----------+-+-------+----------+----+-------+-------+
. | |+ | | | | |
. | [10ľF] | | | | [100K]
. | | | | | | |
. | GND | +---|----|-------|-------+
. | | | | | | |
. [R1] +---+---+ | | [Rt] +---+---+ |
. | |_ Vcc_| | | | |_ Vcc _| |
. +---------------O|D R|O-+ | +--O|D R|O--+
. | 1 S1B | | | | | | |
. +-[R2]-O<--O--+--|TH 7555| [10K] [Ct] |TH 7555| 100nF
. | 2 | |__ | | | |_ | |
. +-[R3]-O +-O|TR OUT|-[C2]-+----|--O|T OUT|---|-->TRIG
. | 3 | | GND | 100nF | | GND | |
. +-[R4]-O [Ct]+---+---+ | +---+---+ |
. | 4 | | | | |
. +-[R5]-O +------+---------------+-------+-------+
. | 5 |
. +-[R6]-O GND
. 6
. O

I've shown the circuit with CMOS 555s.

If you choose to use bipolars, connect a 100nF ceramic cap directly
across the Vcc and GND pins on each chip.

Do you need a circuit description?

You might be able to use a single 555, but for the extra buck or so,
I'd go with the fixed width trigger.

BTW, what are the intervals you're interested in?
Click to expand...
---
Oops...
_
D and TH of the one-shot are supposed to be connected together, like
this:

.. 1 S1A C
..Vcc>------+--O<--O
.. | 2 |
.. +--O |
.. | 3 |
.. +--O |
.. | 4 |
.. +--O |
.. | 5 |
.. +--O |
.. 6 |
.. O |
.. |
.. |
.. |
.. +----------+-+-------+----------+----+-------+-------+
.. | |+ | | | | |
.. | [10ľF] | | | | [100K]
.. | | | | | | |
.. | GND | +---|----|-------|-------+
.. | | | | | | |
.. [R1] +---+---+ | | [Rt] +---+---+ |
.. | |_ Vcc_| | | | |_ Vcc _| |
.. +---------------O|D R|O-+ | +--O|D R|O--+
.. | 1 S1B | | | | | | |
.. +-[R2]-O<--O--+--|TH 7555| [10K] +---|TH 7555| 100nF
.. | 2 | |__ | | | |_ | |
.. +-[R3]-O +-O|TR OUT|-[C2]-+----|--O|T OUT|---|-->TRIG
.. | 3 | | GND | 100nF | | GND | |
.. +-[R4]-O [Ct]+---+---+ [Ct] +---+---+ |
.. | 4 | | | | |
.. +-[R5]-O +------+---------------+-------+-------+
.. | 5 |
.. +-[R6]-O GND
.. 6
.. O


---
JF
 
George wrote:
The old Radio Shack catalog had two rotary switches. One was a
12-pole, 1-position, shorting. The other was a 2-pole, 6 position,
non-shorting. The second one is the only one left now:

http://www.radioshack.com/product/index.jsp?productId=2062536

I don't understand the lingo. Can someone point me to schematic
symbols for these two switches, or an explanation of what they do?
And what is the "shorting" thing all about.

More generally, I'm making an intervalometer for my camera, and in
order to change the period between pictures, I need to vary one of
the 555 timer resistors. And I thought a multi-position switch of
some kind, with individual resistors, might work better than a
pot. But I also need an on/off switch for the whole thing. Can the
R/S rotary switch be rigged to do both functions?

Thanks for any help.
Click to expand...
You can use the RS switch to select 6 positions: off is the first
position. When you turn it to the next position, you select all
the resistors, R1 through R5, next position R2 through R5, etc.


+Vcc
|
+---to 555 Pin7 |
| |
[R1] |
| |
+----+ |
| | |
[R2] | |
| | |
+--+ | |
| | | o | o
[R3] | +-o +--o
| +---o +--o
+------o<----o +--o<----o---To 555 pin 8
[R4] +---o | +--o
| | +-o | +--o
+--+ | |
| | +----------------to 555 pin 6
[R5] |
| |
+----+
|
[C1]
|
Gnd

Obviously, only a partial schematic. Don't forget to sum the
resistors when computing the Rtot C times.

Ed
 
John Fields says...

A 2-pole 6 position non-shorting switch would be one
with 2 commons and 6 contacts per common

But I also need an on/off switch for the whole thing.
Can the R/S rotary switch be rigged to do both
functions?

Yes.
Click to expand...
Thanks very much for your reply.

Ok, on this point, so the R/S switch is really just two
single pole switches ganged together. Then that may be the
lowest cost and best solution. I'm trying to make this as
cheap and easy as possible for others, with everything
available at R/S. I actually have the R/S 1meg linear pot,
and it's not worth a damn - the first 30 degrees on one side
produces no change at all. And, they no longer sell the
add-on switch for that pot. So if the rotary switch can do
timing plus on/off, then that's going to work best.

If what you mean by "intervalometer" is an astable where
you use the output pulse to trigger the camera and the
period between output pulses to determine the frequency
of the trigger pulses, then the answer is "yes" if you
use two 555's; one as an astable to generate the time
intervals and the other as a monostable to generate a
fixed-width trigger pulse for the camera

You might be able to use a single 555, but for the extra
buck or so, I'd go with the fixed width trigger.
Click to expand...
Yes, that's what I mean by intervalometer, but I don't see
the need for the second timer section. The shutter-press
pulse duration will be the discharge period of the first
timer section, and that's determined solely by the value of
the discharge resistor, which isn't going to change. I've
found that I get a bit under two seconds of shutter trigger
with a 100ufd cap and a 22k resistor, and that period isn't
going to change no matter what I do with the interval
between shutters (the charge period). I've breadboarded
this, and it does work. Unless I'm missing something.

[As an aside, I found that you can almost completely
isolate the charge and discharge times by putting a diode
parallel to the discharge resistor forward-biased toward the
cap, so that the cap charges through the charge resistor and
the diode, but discharges though the discharge resistor.
That's how I get a <50% duty cycle when I need it.]

Do you need a circuit description?
Click to expand...
No I don't think so.

BTW, what are the intervals you're interested in?
Click to expand...
Well, this is pretty much a short term intervalometer, with
an interval between pictures of about 1 minute or less. The
1meg pot is about right for the charge resistor, or the
equivalent using the switch. It would be nice to provide
for longer intervals, but I just don't know how big a
resistor I can use with a bipolar 555 and an electrolytic cap
- leakage and such.

But coming back to the second timer section. I'm also doing
a second version where there are actually two shutter
pulses, the first being a "half-press" contact, which causes
the camera to autofocus, etc., and the second being the
actual shutter contact. The first contact needs to stay
engaged while the second takes place. So I need the
half-press pulse to last for, say, two seconds, and the
shutter pulse needs to begin one second into the first
pulse. Then both should terminate together.

For that, I use the second timer section purely as a
flip-flop. I connect the output of the first section to the
trigger and threshhold of the second through a circuit that
provides a one-second delay going low, but an immediate
response going high - through a diode. Well, I'm in the
process of drawing this up, and will post it in the
schematics newsgroup.

Thanks again for your help with the switch. Let me know if
there's something I haven't considered re needing another
timer section for the pulse period.
 
On Sun, 31 Oct 2010 17:04:09 -0500, George <gh424NO824SPAM@cox.net>
wrote:

John Fields says...

A 2-pole 6 position non-shorting switch would be one
with 2 commons and 6 contacts per common

But I also need an on/off switch for the whole thing.
Can the R/S rotary switch be rigged to do both
functions?

Yes.

Thanks very much for your reply.

Ok, on this point, so the R/S switch is really just two
single pole switches ganged together. Then that may be the
lowest cost and best solution. I'm trying to make this as
cheap and easy as possible for others, with everything
available at R/S. I actually have the R/S 1meg linear pot,
and it's not worth a damn - the first 30 degrees on one side
produces no change at all. And, they no longer sell the
add-on switch for that pot. So if the rotary switch can do
timing plus on/off, then that's going to work best.

If what you mean by "intervalometer" is an astable where
you use the output pulse to trigger the camera and the
period between output pulses to determine the frequency
of the trigger pulses, then the answer is "yes" if you
use two 555's; one as an astable to generate the time
intervals and the other as a monostable to generate a
fixed-width trigger pulse for the camera

You might be able to use a single 555, but for the extra
buck or so, I'd go with the fixed width trigger.

Yes, that's what I mean by intervalometer, but I don't see
the need for the second timer section. The shutter-press
pulse duration will be the discharge period of the first
timer section, and that's determined solely by the value of
the discharge resistor, which isn't going to change.
Click to expand...
---
If you're using the discharge time for the shutter press then there
should be no need for a second timer section since, as you mention,
the dicharge time will remain constant regardless of the oscillator's
frequency.

My concern was that if you were using the charge time pulse for the
shutter-press signal, then the variation of its period with the
oscillator's frequency might make the camera unhappy.

Such being the case, a constant-width frequency-independent pulse
generated by a second timer would make that problem go away.
---

found that I get a bit under two seconds of shutter trigger
with a 100ufd cap and a 22k resistor, and that period isn't
going to change no matter what I do with the interval
between shutters (the charge period). I've breadboarded
this, and it does work. Unless I'm missing something.

[As an aside, I found that you can almost completely
isolate the charge and discharge times by putting a diode
parallel to the discharge resistor forward-biased toward the
cap, so that the cap charges through the charge resistor and
the diode, but discharges though the discharge resistor.
That's how I get a <50% duty cycle when I need it.]
Click to expand...
---
Yeah, that's a nice trick. :)
---


Do you need a circuit description?

No I don't think so.

BTW, what are the intervals you're interested in?

Well, this is pretty much a short term intervalometer, with
an interval between pictures of about 1 minute or less. The
1meg pot is about right for the charge resistor, or the
equivalent using the switch. It would be nice to provide
for longer intervals, but I just don't know how big a
resistor I can use with a bipolar 555 and an electrolytic cap
- leakage and such.
Click to expand...
---
I'd be leery of trying anything much longer than a few minutes without
checking the cap leakage, especially if you're going to be using Radio
Shack parts.

If you need longer intervals they can be easily (and cheaply) obtained
by using digital methods.
---

But coming back to the second timer section. I'm also doing
a second version where there are actually two shutter
pulses, the first being a "half-press" contact, which causes
the camera to autofocus, etc., and the second being the
actual shutter contact. The first contact needs to stay
engaged while the second takes place. So I need the
half-press pulse to last for, say, two seconds, and the
shutter pulse needs to begin one second into the first
pulse. Then both should terminate together.
Click to expand...
---
Like this?:

|<---- 2s---->|
_____________
T1___| |_____

1s->| |<--
______
T2_________| |_____


For that, I use the second timer section purely as a
flip-flop. I connect the output of the first section to the
trigger and threshhold of the second through a circuit that
provides a one-second delay going low, but an immediate
response going high - through a diode. Well, I'm in the
process of drawing this up, and will post it in the
schematics newsgroup.
Click to expand...
---
I'll be looking for it. :)
---

Thanks again for your help with the switch. Let me know if
there's something I haven't considered re needing another
timer section for the pulse period.
Click to expand...
---
You're welcome.

So far you seem to have it pretty much under control.

---
JF
 
On Sun, 31 Oct 2010 15:51:21 -0400, ehsjr <ehsjr@nospamverizon.net>
wrote:

George wrote:
The old Radio Shack catalog had two rotary switches. One was a
12-pole, 1-position, shorting. The other was a 2-pole, 6 position,
non-shorting. The second one is the only one left now:

http://www.radioshack.com/product/index.jsp?productId=2062536

I don't understand the lingo. Can someone point me to schematic
symbols for these two switches, or an explanation of what they do?
And what is the "shorting" thing all about.

More generally, I'm making an intervalometer for my camera, and in
order to change the period between pictures, I need to vary one of
the 555 timer resistors. And I thought a multi-position switch of
some kind, with individual resistors, might work better than a
pot. But I also need an on/off switch for the whole thing. Can the
R/S rotary switch be rigged to do both functions?

Thanks for any help.


You can use the RS switch to select 6 positions: off is the first
position. When you turn it to the next position, you select all
the resistors, R1 through R5, next position R2 through R5, etc.


+Vcc
|
+---to 555 Pin7 |
| |
[R1] |
| |
+----+ |
| | |
[R2] | |
| | |
+--+ | |
| | | o | o
[R3] | +-o +--o
| +---o +--o
+------o<----o +--o<----o---To 555 pin 8
[R4] +---o | +--o
| | +-o | +--o
+--+ | |
| | +----------------to 555 pin 6
[R5] |
| |
+----+
|
[C1]
|
Gnd

Obviously, only a partial schematic. Don't forget to sum the
resistors when computing the Rtot C times.

Ed
Click to expand...
---

+Vcc
|
+---to 555 Pin7 |
| |
[R1] |
| |
+----+ |
| | |
[R2] | |
| | |
+--+ | |
| | | o | o
[R3] | +-o +--o
| +---o +--o
+------o<----o +--o<----o---To 555 pin 8
[R4] +---o | +--o
| | +-o | +--o
+--+ | |
| | +----------------to 555 pins 2&6
[R5] | |
| | [Ct]
+----+ |
GND


Yes? :)

---
JF
 
I've posted the circuit and explanation to the
alt.binaries.schematics.electronics newsgroup under the subject:

Two Stage Intervalometer for Canon XT and similar cameras
 
John Fields wrote:
On Sun, 31 Oct 2010 15:51:21 -0400, ehsjr <ehsjr@nospamverizon.net
wrote:


George wrote:

The old Radio Shack catalog had two rotary switches. One was a
12-pole, 1-position, shorting. The other was a 2-pole, 6 position,
non-shorting. The second one is the only one left now:

http://www.radioshack.com/product/index.jsp?productId=2062536

I don't understand the lingo. Can someone point me to schematic
symbols for these two switches, or an explanation of what they do?
And what is the "shorting" thing all about.

More generally, I'm making an intervalometer for my camera, and in
order to change the period between pictures, I need to vary one of
the 555 timer resistors. And I thought a multi-position switch of
some kind, with individual resistors, might work better than a
pot. But I also need an on/off switch for the whole thing. Can the
R/S rotary switch be rigged to do both functions?

Thanks for any help.


You can use the RS switch to select 6 positions: off is the first
position. When you turn it to the next position, you select all
the resistors, R1 through R5, next position R2 through R5, etc.


+Vcc
|
+---to 555 Pin7 |
| |
[R1] |
| |
+----+ |
| | |
[R2] | |
| | |
+--+ | |
| | | o | o
[R3] | +-o +--o
| +---o +--o
+------o<----o +--o<----o---To 555 pin 8
[R4] +---o | +--o
| | +-o | +--o
+--+ | |
| | +----------------to 555 pin 6
[R5] |
| |
+----+
|
[C1]
|
Gnd

Obviously, only a partial schematic. Don't forget to sum the
resistors when computing the Rtot C times.

Ed


---

+Vcc
|
+---to 555 Pin7 |
| |
[R1] |
| |
+----+ |
| | |
[R2] | |
| | |
+--+ | |
| | | o | o
[R3] | +-o +--o
| +---o +--o
+------o<----o +--o<----o---To 555 pin 8
[R4] +---o | +--o
| | +-o | +--o
+--+ | |
| | +----------------to 555 pins 2&6
[R5] | |
| | [Ct]
+----+ |
GND


Yes? :)

---
JF
Click to expand...
Yes! Much better. :) Thanks!

Ed
 
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