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slr 5000 28th April 2008 12:49 AM

remote control for preamp
 
hi guys im trying to set up a remote volumew control for my ska pre .im using the greg ball optical volume control so im after something i could just use as a motor to turn it . id also like to hook it to a led display (blue of course) that would display volume from 1 to 10 .its a simple idea but i dont know what to use to do it .im in aus so it would be great if i could get the parts from here to do it . thanks in advance for any help

Jonathan Bright 28th April 2008 01:41 AM

Hi sir 5000, the new JAYCAR catalogue has a number of small electric motors and gear sets. Some of these are Tamiya I think so the quality should be okay. BTW there is a kit for a remote volume contol with a motor and conventional potentiometer around. Came out of Silicon Chip I guess. I don't know whether you've checked that out. Probably in the JAYCAR cat' too. Not the same as your idea of course but the motor may be useful. I noticed today that ROCKBY (down Clayton way) have an Analogue Devices digital volume control chip (AD71110KN or something like that I think) on special this monring. Check it out soon as they've decided to change their specials very frequently lately i.e. daily) Good luck Jonathan

(Pity about Essendon! I'm just far enough away these days not to feel too much pain!)

gain 28th April 2008 04:43 AM

an idea for the display ...

use a 7447 bcd to 7 segment decoder to drive the blue led display. use a 1 of 8 encoder to drive the low order 3 of the 7447 bcd inputs. this would give you a 0-7 on the display by activating the appropriate input pin on the decoder. to get 8 and 9 on the display, use some combinational logic that when 8 or 9 is called for, the high order bit on the 7447 is turned on, along with the 0 or 1 input pin on the decoder (0 for 8 and 1 for 9).

so, at this point you will have ten connections, and by applying (or removing) logic level voltage to one of them you can put any number from 0-9 on the display. make sence so far?

ok now connect those ten wires, each representing one number, to an LM3916 dot/bar display driver set for 'dot' mode. connect the analog sensing input of the 3916 to a voltage divider which includes a pot which is mechanically coupled to your volume control.

as the volume level is increased, the voltage applied to the input of the 3916 will also rise, causing it to turn on successively higher numbered 'dots'. now, instead of the dots being 10 LED's, they are logic level connections to the decoder representing 0-9, so the numbers on the 7 segment display will count upwards as the 'dots' rise.

or you could just use a PIC / BASIC stamp and write a few lines of computer code to do the same thing.

slr 5000 28th April 2008 10:31 PM

thanks for your help guys i was hoping there would be something i could just plug in and it would do the rest . ive seen the led displays at altronics which look good but i presume i have to use some sort of chip/controler to make these work is this correct

gain 28th April 2008 11:21 PM

Quote:

Originally posted by slr 5000
thanks for your help guys i was hoping there would be something i could just plug in and it would do the rest . ive seen the led displays at altronics which look good but i presume i have to use some sort of chip/controler to make these work is this correct
yeah the 7447 is the chip that controls the display. google 7447 or 74LS47 for the datasheet. basically, it has one output pin for each of the seven segments on the display, and four input pins (not counting power supply pins).

the four input pins on the 7447 correspond to each digit of a four bit binary number. through application of logic ON or logic OFF voltage levels (typically +5V and 0V respectively), you apply a four bit binary number to the four input pins. whatever binary number you applied would be displayed (in decimal) on the 7 segment display.

for example, assume the input pins of the 7447 are called B0, B1, B2, and B3 with B0 being the low order (least significant) bit. to put, say, a "7" on the LED display, you would connect B0 to +5V, B1 to +5V, B2 to +5V, and B3 to 0V. This would give you 0111, or "7" in binary, at the input which would result in a "7" being lit on the display.

this is an overview of the display driver section. if you are interested in possibly implementing this let me know and i will provide schematic of the whole thing, from vol pot to LED display.

slr 5000 28th April 2008 11:49 PM

hi mate im definately interested in trying it .ill even post some pics once its done . cheers

gain 29th April 2008 02:08 AM

2 Attachment(s)
this is what i had in mind.

you may need pull up resistors between the ten 3916 output pins and Vcc, depending on what type of AND gate you use.

Coulomb 29th April 2008 02:42 AM

Try here
http://www.diyaudio.com/forums/showt...threadid=42589


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