[sdiy] A quick Norton amp question....

[Dave Kendall]

Thanks to all for the replies. It's a cut-down version of the serge 
triple waveshaper I'm working on. I'll leave the unused amps floating.
The pinout is weird for sure, but at least the V+ and GND pins are laid 
out like most standard logic ICs.

cheers,
Dave


> On Dec 6, 2011, at 04:55, aankrom wrote:
>
>> Wasn't there speculation that the pinout had to do with a specific 
>> design that the LM3900 was designed for. Still... Insane...
>>
>> AA
>>>> Hi All.
>>>>
>>>> Unused sections of a quad Norton amp - should they be wired like a
>>>> conventional op-amp with OUT and NEG inputs joined, and POS input to
>>>> GND?
>>>> Anything else to watch for?
>>>>
>>>> cheers,
>>>> Dave
>>>>
>>
>> NO! LM3900 inputs are a pn junction to - supply, so you should have
>> a current limiting resistor between any voltage source and an input.
>> If you must connect output to input, put a 1M resistor between them
>> and tie the other input to +supply via a 2M2.
>>
>>
>> Serge Modular sometimes left unused LM3900s completely
>> unconnected, and these modules have been produced for 35 years
>> - Serge really understood the LM3900.
>>
>>
>> I recommend spending some time with the data sheet and app note 72
>> before playing with the 3900 etc.
>>
>> Steve
>>
>>> On Tue, 6 Dec 2011 12:22:47 +1100, Paul Perry wrote:
>>> My intuitive feeling is that you can let them all float,
>>> seeing that it is a current amplifier implying low impedance input,
>>> and there isn't going to be any problem wiht the output floating.
>>> My main problem with the LM3900 is the pinout, a total mindfuck..
>>>
>>> paul perry
>>> Melbourne Australia