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Old 13th December 2012, 01:28 AM   #1
docb is offline docb  United States
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Default simple VCA IC?

I only want to control volume with a voltage control. Is there a simple IC that will do just this?

(Just on/off switching would be ok as well if it had some x crossing click protection built in)
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Old 13th December 2012, 09:50 PM   #2
Spiny is offline Spiny  United Kingdom
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Quote:
Originally Posted by docb View Post
I only want to control volume with a voltage control. Is there a simple IC that will do just this?

(Just on/off switching would be ok as well if it had some x crossing click protection built in)
I've used the ssm2018pz from analog devices to add a remote volume control to a 70's amp in the past - the addon uses a PIC to handle the IR control decoding and generate the control voltages.
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Old 14th December 2012, 04:49 AM   #3
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CA3080
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Old 14th December 2012, 04:58 AM   #4
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The CA3080 is, by todays standards a bad choice. Look at the THAT2180 etc: THAT Corporation Audio Technology and check their appnotes. E
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Old 14th December 2012, 05:15 AM   #5
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Quote:
Originally Posted by docb View Post
I only want to control volume with a voltage control. Is there a simple IC that will do just this?

(Just on/off switching would be ok as well if it had some x crossing click protection built in)
What the others are saying is true about the SSM and THAT chips but if you're skeptical of a serial controlled chip like the PGA2310 there's lots of help available on Pics, Intel MCS51 family and may favorites Freescale 68HC08 family.

Microcontrollers can add all sorts of 'smarts' from remote control to power on mute sequencing. For those who really like 'pots' you can use shaft encoders as inputs. I use an 8 bit micro in the TV PC to shut it down after 6 hours. It's 'smart' enough to ping the power switch (via relay) and wait 2 minutes and force the power switch if for some reason it didn't go peacefully.

G
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Old 14th December 2012, 05:56 AM   #6
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Quote:
Originally Posted by docb View Post
I only want to control volume with a voltage control. Is there a simple IC that will do just this?
AD603 sounds just great to my ears, very simple to use. None of the SQ problems of the other types (VCAs, CMOS opamps).
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Old 14th December 2012, 06:03 AM   #7
docb is offline docb  United States
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I'm really looking for something like the TDA7052A but no amplifier.

These would be good too, but the package is a bit small
MAX4744, MAX4744H, MAX4745, MAX4745H, MAX4746H Low-Voltage, Dual SPDT, Audio Clickless Switches with Negative Rail Capability - Overview
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Old 14th December 2012, 08:29 AM   #8
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Originally Posted by abraxalito View Post
AD603 sounds just great to my ears, very simple to use. None of the SQ problems of the other types (VCAs, CMOS opamps).
It's a fine chip. I used them in the font end on the optical pickups in a high def film to video (telecine) running them up to 30 MHz. Down side is they only have 40 dB control range and are limited to a few Volts p-p. Not much headroom for audio work. AIUI the chips were intended for variable gain IF amplifiers.

G
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Old 14th December 2012, 08:41 AM   #9
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Subjectively there's no problem at all as post amplifier after I/V conversion with passive resistor in my DAC. I had been concerned about LF noise for your mentioned reasons, but it does well enough - most CDs are noisier.
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Old 17th December 2012, 05:08 AM   #10
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TDA 7630 but more than what u want.

Gajanan Phadte
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