how to substitute CA3080 with LM13700

[creekree]

hi all,

i am working on a double thomas henry vco-1.

i want to use a single LM13700 instead of two CA3080, but i am a little unsure about what to do with the pins of the LM13700 that the CA3080 does not have:
buffer input, buffer output, diode bias.

am i supposed to connect them to ground of should i leave them floating? (i suspect the latter is not the case)

also, is "input (+)" (pin 3 / 14) the non-inverting or the inverting input on the LM13700?

[Clack]

you can leave the diode bias unconnected ive seen it done in many circuits as for the buffers , In the datasheet it mentions grounding the input and leaving the output unconnected when it specifies the electrical characteristics.

yup

non-inverting = +

[creekree]

thanks for the answer Mr Clack, this info helps me a lot.

[Luka]

im looking to do the opposite of creekee here
i have a stockpile of 3080s and wish to convert a simple 13700 design to use 3080s. Will adding 2 matched 4148s be a reasonable substitute for the diode bias input on the 13700?

[CJ Miller]

Another option is to just use the 13600 instead and not worry about the diodes at all. Incidentally, National lists the LM13x00 as obselete, but the Japanese NJM versions are fine also. I bought 100x NJM13600 from Mouser for a good price.

[andrewF]

This is a good topic, especially as 3080s are now more expensive and rarer than 13700s.
Had a look around, found this page -
http://www.musicianshotline.com/archive/monthly/pedal_power/0605.htm

and

http://machines.hyperreal.org/categories/DIY/chips/3080.vs.13700.txt