[sdiy] Op-amp to boost VC signal with +5V/GND?

[mikas]

Many thanks to all,

This time I'll use +8V or so PSU to power up op-amp. +5V for GATE will
work well for my next (or first :) ) project.

Mikas

2010/7/29, René Schmitz <uzs159 at uni-bonn.de>:
> Hi Mykolas,
>
> mikas schrieb:
>> Hi guys,
>>
>> My project is slowly moving forward.
>> http://www.analogas.uzrasai.lt/tag/seq/ ( LT at the moment only, EN
>> coming soon).
>>
>> 1. Could You recommend me an op-amp to boost VC signal with single
>> +5V/GND power supply? I don't want to make PSU with +12V/gnd/-12V (or
>> 15V) just for boosting VC signal. I've made simple +5V with 7805 to
>> use with external +8V PSU. I want to keep it simple.
>>
>> http://www.analogas.uzrasai.lt/wp-content/uploads/2010/07/seq1.jpg
>>
>> Can I use TLC27? Or other recomendations. My local shops are a bit
>> limited, ex: http://www.rcl.lt/index.php?id=2&lang=en&acc=show&fid=644
>
> They should be fine, if you power them from your 8V supply. That ensures
> that you can get output up to 5V. (They can't hit the positive rail.)
>
> Looking at your schematic, one additional remark: I would change that
> arrangement for the portamento. As shown you charge up that 22u cap
> directly from the multiplexer when you have switched porta off. That
> could mean a high current through the multiplexer. I would put a 1k or
> so resistor between the cap and the + input of the opamp. The "off"
> coming from the switch going to the + input directly.
>
>> 2. Also, can I drive GATE with two 40106 as shown in schematics? Idea
>> taken from MFOS.
>
> Yes.
>
> Cheers,
>   René
>
> --
> uzs159 at uni-bonn.de
> http://www.uni-bonn.de/~uzs159
>


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Mykolas
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