Re: Switching +/-12V from 6/0V



George wrote:
In article <1184356345.100537.33400@xxxxxxxxxxxxxxxxxxxxxxx
s.com>, dagmargoodboat@xxxxxxxxx says...


You could also do something like this:


+10v
R1 ---
input >--[1k]---. |
| Q1 +------+
'>| PNP | |
|---. [load] |
/| | | |
| --- +-|>|--+ D1
| GND |
| |/
+------------| Q2
R2 | |>. NPN
[10k] |
| |
+--------------+--- -10v


Thanks very much. So it WAS possible to do it with two
transistors - you just have to know how. :-)

I ended up using your configuration, James, but with
resistors in different places to reduce switching current:

+10v
---
input >---------. Q1 |
(+6V/GND) | PNP +------+
'>| | |
|-[47k]-. [load] |
/| R1 | | |
| --- +-|>|--+ D1
| GND |
| R2 |/
+-[10k]-+----| Q2
| |>. NPN
R3 [470k] |
| |
+------+--- -10v

And it works fine. Actually, it works fine without R3, but
it doesn't hurt to have it there.


You're missing a few details, that circuit is marginal for this application. Something more along the lines of this is better than "fine":
View in a fixed-width font such as Courier.

..
..
.. +6V
.. -
.. R2| +10v
.. R1 [47k] ---
.. input >---[1k]--. | |
.. (+6V/GND) | | +------+
.. '>| |1N914A | |
.. Q1 |-+-|>|-. [load] |
.. PNP /| | | |
.. | --- +-|>|--+ D1
.. | GND |
.. | |/
.. +------------| Q2
.. R3| |>. NPN
.. [1k] |
.. | |
.. '--------------+--- -10v
..
..
..



.

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