I'm wondering if someone could please help out a novice...
I'm trying to build the following circuit, but my local supplier, RadShack, only carries N-Channel FETS, not P-Channel as specified by the schematic. Can someone recommend a simple solution with NFETS, or perhaps an alternative altogether.
Here is the circuit:
Which is actually part of this document regarding driving higher current LEDS with the MAX7219:
Thanks!
-Brad
Brad, you can also save a lot of money taking these bipolar PNP transistors instead. They can switch around 100mA max. If the driver voltage is higher, you can insert a cascode stage similar to the drawing in the data sheet.
Vdriver +--------+----------o | | less than 10V .-. | 1k| | | | | | '-' | | |< +------| 2N3906 | |\ .-. | 1.8k| | | | | anode digit drive '-' | o Dig0...Dig7
Vdriver +--------+----------o | | more than 8V .-. | 1k| | | | | | '-' E| | |< +------| 2N3906 | B |\ .-. |C | | | 1k| | anode digit drive '-' |C |/ +5V o------| 2N3904 B |>
E| .-. | | 1k| | '-' | o------+ Dig0... created by Andy´s ASCII-Circuit v1.22.310103 Beta
ciao Ban
That looks like the advice I was looking for. I'm pretty good with digital electronics, but analog still holds many mysteries for me.
Thanks!
transistors
Use one of these for Q2.
Radio shack P#
900-5549 VP0300L Vds= -30V Id= 0.320 Amp TO-92 $.99 900-5548 VP0300B Vds= -30V Id= 1.250 Amp TO-39 $6.59 900-5194 IRF9510 Vds= -100V Id= 4.0 Amp TO-220 $1.16You can order it from your local R/S or call 1 800 442 7221
Good luck, Cyrus ( please reply to group )
RadShack,
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