www.megadrum.info

This eight-channel CMOS analog multiplexer/demultiplexer is pin compatible with the ’4051 function and,
additionally, features injection-current effect control, which has excellent value in automotive applications where
voltages in excess of normal supply voltages are common.
The injection-current effect control allows signals at disabled analog input channels to exceed the supply
voltage without affecting the signal of the enabled analog channel. This eliminates the need for external
diode/resistor networks typically used to keep the analog channel signals within the supply-voltage range.

Why not use this component ?

http://fr.farnell.com/jsp/Semiconducteurs/Logiques/TEXAS+INSTRUMENTS/SN74HC4851D/displayProduct.jsp?sku=9591532

Here is my new All In One PCB design with 74HC4851 !!! (NEW VERSION Update 16/01/2008)








**** PINOUTS ****


USB Connector :

1 - VCC 5V (pin 1)
2 - D- (pin 2)
3 - D+ (pin 3)
4 - GND (pin 4)


MIDI IN OUT Connector :

1 - MIDI OUT + (pin 4)
2 - MIDI OUT - (pin 5)
3 - MIDI OUT GND (pin 2)
4 - MIDI IN + (pin 4)
5 - MIDI IN - (pin 5)


MIDI LED Connector :

1 - Led -
2 - Led +


KeyBoard Connector :

1 - Right
2 - Up
3 - Down
4 - Left
5 - GND


LCD Connector :

1 - GND (pin 1)
2 - VDD (pin 2)
3 - VEE (pin 3)
4 - RS (pin 4)
5 - RW (pin 5)
6 - E (pin 6)
7 - D0 (pin 7)
8 - D1 (pin 8)
9 - D2 (pin 9)
10 - D3 (pin 10)
11 - D4 (pin 11)
12 - D5 (pin 12)
13 - D6 (pin 13)
14 - D7 (pin 14)
15 - Led + (backlight)
16 - Led - (backlight)


ICSP 18F2550 Connector :

1 - MCLR Vpp
2 - VCC 5V
3 - GND
4 - PGD (Data)
5 - PGC (Clock)
6 - PGM (LVP)


ICSP Atmega32 Connector :

1 - MISO (PB6)
2 - MOSI (PB5)
3 - SCK (PB7)
4 - RESET
5 - GND


32 INPUTS Connector :

1 - GND
2 - GND
3 - power source for HiHat controller
4 - HiHat controller input
5 - Kick
6 - NC
7 - HIHat Bow
8 - HiHat Edge
9 - Snare Head
10 - Snare Rim
11 - Ride Bow
12 - Ride Edge
13 - Crash Bow
14 - Crash Edge
15 - Tom1 Head
16 - Tom1 Rim
17 - Tom2 Head
18 - Tom2 Rim
19 - Tom3 Head
20 - Tom3 Rim
21 - GND
22 - GND
23 - Tom4 Head
24 - Tom4 Rim
25 - Aux1 Head/Bow
26 - Aux1 Rim/Edge
27 - Aux2 Head/Bow
28 - Aux2 Rim/Edge
29 - Aux3 Head/Bow
30 - Aux3 Rim/Edge
31 - Aux4 Head/Bow
32 - Aux4 Rim/Edge
33 - Aux5 Head/Bow
34 - Aux5 Rim/Edge
35 - Aux6 Head/Bow
36 - Aux6 Rim/Edge
37 - Aux7 Head/Bow
38 - Aux7 Rim/Edge
39 - GND
40 - GND

Nice one....
You save a lot of money (diods are cheap, but buy 64 or 128 of the little nasty buggers and it adds up to 10 or 15$)
And you save soldering and design work too.....

I wish you had this idea like 2 months ago , you meanie !

Lakedaemon wrote:I wish you had this idea like 2 months ago , you meanie !

I had this idea 3 days ago ...

I have seen that the link you post for the 74HC4851D is superficial type of mount. Isn't your board for pin mounts?

elrules wrote:I have seen that the link you post for the 74HC4851D is superficial type of mount. Isn't your board for pin mounts?

You can choose the DIP version : 74HC4851N
Or the CMS version with an adapter.

Will you make the Diptrace files available for your board ?

TriggerThis wrote:Will you make the Diptrace files available for your board ?

Layers are available.

I want to modify it, I dont need the USB part, the LCD and the keys, and I'de like to add capacitors to each ICs VCC pins, and also some kind of buffering for the MIDI out.

I wanna make a poor man's megadrum for a friend. I dont have problems with the schematics but I'm not used to making PCBs with diptrace (read not good enough). I figure modifying an existing desing would be easier

BTW, how did you find out about the 74HC4851 ?

In the old days, when there was only TTL, CMOS and analog ICs, I had a big ECG book with schematics for all the ICs along with part number, pinouts and a brief description of the fucntions. It was really easy to browse the book to select a chip because ou didnt have to go trought the datasheet to know what it did.

Do you know of a web site with a IC browser lilke that ?

I've downloaded the TI (texas instruments) product selection guide in PDF and also some other documents, but I found nothing like the ECG book I had in the old days.

TriggerThis wrote:I want to modify it, I dont need the USB part, the LCD and the keys, and I'de like to add capacitors to each ICs VCC pins, and also some kind of buffering for the MIDI out.
I wanna make a poor man's megadrum for a friend. I dont have problems with the schematics but I'm not used to making PCBs with diptrace (read not good enough). I figure modifying an existing desing would be easier

Right.

TriggerThis wrote:BTW, how did you find out about the 74HC4851 ?

I am curious ... And I try something new for us ...

TriggerThis wrote:In the old days, when there was only TTL, CMOS and analog ICs, I had a big ECG book with schematics for all the ICs along with part number, pinouts and a brief description of the fucntions. It was really easy to browse the book to select a chip because ou didnt have to go trought the datasheet to know what it did.
Do you know of a web site with a IC browser lilke that ?

No.