Driving two transistors with same signal...

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vic...

Posted: Sat May 10, 2008 8:39 pm

Guest

petrus bitbyter wrote:

Quote:

Didn't you see my four transistors, four resistors solution yesterday?

+--------+------------------+-------+--Vcc
| | | |
___ |< | ___ |/ |
in----+--|___|---| | +--|___|--| |
| |\ | | |> |
| | | | | |
| | |< | | |
| +------| | +-----|
| | |\ | | |\
| .-. | | .-. |
| | | .---. | | | .---.
| | | | | | | | | |
| '-' | D | | '-' | D |
| | | | | | | |
| | '---' | | '---'
| | | | | |
------)------------+--------+------)-----------+-------+--GND
| |
+----------------------------+
created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de

Sorry I missed your post. Looks like a good solution. Thanks !

vic...

Posted: Sat May 10, 2008 9:11 pm

Guest

Thank you to all for your support.

I solved my problem temporarily by using the "bias Vbe to 0.5V"
solution. However I had some issues with the transistors still leaking
some current when OFF, and not having the same current when ON. I
reduced Vbe even more to make the OFF current not visible on the
displays, and ON current almost equal. Still not as pleasing visually as
separate drives for each transistor.

The 5 transistors solution seems definately more reliable and less
sensitive to resistor values.

Next time, I'll make sure to use one signal to control each display :)

Thanks again.

petrus bitbyter...

Posted: Sun May 11, 2008 3:14 pm

Guest

"vic" <news at (no spam) bidouille.org> schreef in bericht
news:48264e41$0$9865$426a74cc at (no spam) news.free.fr...

Quote:

petrus bitbyter wrote:
Didn't you see my four transistors, four resistors solution yesterday?

+--------+------------------+-------+--Vcc
| | | |
___ |< | ___ |/ |
in----+--|___|---| | +--|___|--| |
| |\ | | |> |
| | | | | |
| | |< | | |
| +------| | +-----|
| | |\ | | |\
| .-. | | .-. |
| | | .---. | | | .---.
| | | | | | | | | |
| '-' | D | | '-' | D |
| | | | | | | |
| | '---' | | '---'
| | | | | |
------)------------+--------+------)-----------+-------+--GND
| |
+----------------------------+
created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de

Sorry I missed your post. Looks like a good solution. Thanks !

Be aware that this schematic does not work. By modifiing my first schematic
(with one display connected to Vcc) to the second (with both diplays
connected to Gnd) I made a mistake. I posted the right schematic few minutes
before your post.

petrus bitbyter

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