MN3002/MN3007 interchangeability

[Mark Hammer]

Here is a terrific little nugget brought to my attention by the ever-observant Tim Larwill.

The Matsushita MN3002 bucket brigade chip is a 512 stage 14-pin DIP.  It is in somewhat short supply (well, relatively speaking).  The MN3007 is a 1024-stage BBD on an 8-pin chip.  It is not exactly the Ford Focus of linear chips in terms of availability, but is in better supply than MN3002's.  It also tends to have better specs in many areas.

Tim was recently looking at the datasheets for these two chips when a striking revelation caught his eye.  But for the exception of the location of the GND pin on each chip, all the other pins line up.  The clock pins are 2/6 (one back from the "start" and two back from the "end") in the MN3007, and 2/12 on the MN3002 (also one back from the "start" and 2 back from the "end").  The complementary outputs are pins 7/8 on the MN3007 and pins 13/14 on the MN3002 (the "last" two pins in each case).  The input is pin 3 in both.

In essence, if you had a layout, or even a finished board for a pedal that used an MN3002, and this MN3002 became fried, you could conceivably lift two pins on the MN3007, run some wire-wrap wire from those pins to their appropriate locations, and simply pop the MN3007 in the socket.

Note, however, that since the 3007 has twice the number of stages as the 3002, you would need to double the clock rate/frequency to achieve/maintain the same absolute time-delay range.  Still a very astute observation, and certain to be a lifesaver for some folks.  You can get the datasheets for these chips here: http://www.synthdiy.com/view/filecat.asp?type=5

Hats off to Tim.

[Fp-www.Tonepad.com]

Interesting.

What about the 3207 instead of the 3007

Puretube thinks you can get highways named after you if you come up with the adaptor :lol:

Fp