Author Topic: OTA VCR question  (Read 1084 times)

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Offline Jan AudioTopic starter

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OTA VCR question
« on: April 24, 2019, 03:56:34 pm »
Hi, i like to have a voltage controlled resistor,
i am looking in the LM13700 datasheet,
there is a single ended resistor schematic
and there is a dual ended schematic.

I dont understand what is a single ended resistor ?
And the schematic is not clear to me, is the input at the + input ?, and the Vout is behind a capacitor ?, why is that ?

I will try the dual ended resistor, will it give exact the same voltage at the output, or will is be different somehow ?
thanks
 

Offline Kleinstein

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Re: OTA VCR question
« Reply #1 on: April 24, 2019, 04:03:33 pm »
The OTA can be used as a variable gain amplifier and this can be reasonably help to simulate a resistor to ground. Simulating a fre floating resistor is way more complicated. In this case I would consider something like a Photomos device like H11F1 - though this is limited to low voltage.
 

Offline Jan AudioTopic starter

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Re: OTA VCR question
« Reply #2 on: April 24, 2019, 04:26:26 pm »
Thanks, only i need 12 volt at least.
 

Offline Jan AudioTopic starter

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Re: OTA VCR question
« Reply #3 on: April 26, 2019, 03:43:39 pm »
Maybe my LM13700 is broken, it takes not a milliamp power when i connect the +
the whole thing dont works.
 

Offline JPortici

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Re: OTA VCR question
« Reply #4 on: April 26, 2019, 03:51:57 pm »
the VCR thing works, check your wiring. You may also have a 13700 with damaged buffers (it's not unusual for that to happen)
 


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