I'm looking for a PCB design for a relay controlled volume potmeter.
Anyone made such a PCB ? I'm trying to build a system like shown in the Pass Aleph P manual.
It looks that relay control has less problems/costs than a analog pot (unless u use a stepped switch)
So if anyone made such thing or has ideas of usefull links....please !
Gr,
Nick
Anyone made such a PCB ? I'm trying to build a system like shown in the Pass Aleph P manual.
It looks that relay control has less problems/costs than a analog pot (unless u use a stepped switch)
So if anyone made such thing or has ideas of usefull links....please !
Gr,
Nick
Banned
Joined 2002
Guys,
Do a search for Panos29, you will find a layout there designed by Panos using the ADC804 for the 64 step ladder as per the Aleph V1.00 volume control.
If you care to be patient however , Wayne Coburn of Passlabs has a remote passive preamp project in the wings which I understand will be 256 steps.
I should think this will be an excellent design looking at Wayne's previous handy work.
Good luck
Ian
Do a search for Panos29, you will find a layout there designed by Panos using the ADC804 for the 64 step ladder as per the Aleph V1.00 volume control.
If you care to be patient however , Wayne Coburn of Passlabs has a remote passive preamp project in the wings which I understand will be 256 steps.
I should think this will be an excellent design looking at Wayne's previous handy work.
Good luck
Ian
Banned
Joined 2002
Aleph P
Hi, all!
I'm also building a new pre-amp, and my plan is to use a remote-kit from here; http://www.circuitsonweb.com/resources/Projects/mir.html
It's so cheap (compared to others) that I just had to take the chance...
I guess it probably will be easier to drive a motor-pot than a relay-based pot with this?
Arne K
NORWAY
Hi, all!
I'm also building a new pre-amp, and my plan is to use a remote-kit from here; http://www.circuitsonweb.com/resources/Projects/mir.html
It's so cheap (compared to others) that I just had to take the chance...
I guess it probably will be easier to drive a motor-pot than a relay-based pot with this?
Arne K
NORWAY
Hi Nick
At this moment I'm doing a layout for the Aleph P volume control on a seperate PCB. I plan for a preamp made out of Aleph L circuitry but with aleph P 1.0 (ADC0804) style volume control.
I've finished boards for Aleph L1.2 PSU and Aleph L1.2 amp boards a few days ago and are currently doing the volume board. I wish to use 8 bits instead of only 6 as in Aleph P, but there is some instability issues in the LSB I have to solve.
If you are interested in this project you have to wait untill I'm finished.
No, realy. It took me less than 1 week to do the PSU and amp boards, but I'm facing examens within three weeks, so I realy don't know. Maby one, maby four weeks.
At this moment I'm doing a layout for the Aleph P volume control on a seperate PCB. I plan for a preamp made out of Aleph L circuitry but with aleph P 1.0 (ADC0804) style volume control.
I've finished boards for Aleph L1.2 PSU and Aleph L1.2 amp boards a few days ago and are currently doing the volume board. I wish to use 8 bits instead of only 6 as in Aleph P, but there is some instability issues in the LSB I have to solve.
If you are interested in this project you have to wait untill I'm finished.
No, realy. It took me less than 1 week to do the PSU and amp boards, but I'm facing examens within three weeks, so I realy don't know. Maby one, maby four weeks.
O.k!
So, as it seems, there is some some demand for my pcb design so I post it here. Note though that my design incorporates and alephL stage mated with aleph p volume control. I should also note that the volume has some kind of instability from time to time but nothing serious.(something has to do with the lsb bit of the adc0804, but i am not a digital wizard). The pre is built some 11 months ago and serves well til now. However I noticed on my scope that when the input is more than 4Volts there is some serious distortion on the waveforms, especially in low setting of the volume control that is probably due to the overloading of the output stage because of the powerfull signal on the small ohmic value of the low settings. If u use it full clockwise it works good to about 20volts rms output.
Sincerely,
Panos
So, as it seems, there is some some demand for my pcb design so I post it here. Note though that my design incorporates and alephL stage mated with aleph p volume control. I should also note that the volume has some kind of instability from time to time but nothing serious.(something has to do with the lsb bit of the adc0804, but i am not a digital wizard). The pre is built some 11 months ago and serves well til now. However I noticed on my scope that when the input is more than 4Volts there is some serious distortion on the waveforms, especially in low setting of the volume control that is probably due to the overloading of the output stage because of the powerfull signal on the small ohmic value of the low settings. If u use it full clockwise it works good to about 20volts rms output.
Sincerely,
Panos
Jens,
Its funny how this thread has popped up since I wrote you asking for your drawing last night...
I prefer Jens design over all of the others here. Perhaps a little more involved but still simple and very elegant. The best feature is the encoder used as the volume control itself. Really slick! I have seen encoders used in a number of Cinema processors made by Dolby...they always work very well, and allow good resolution....they also never get dirty!!! Some time this week I will work up a PCB for it, unless someone else beats me to it.
Mark
Its funny how this thread has popped up since I wrote you asking for your drawing last night...
I prefer Jens design over all of the others here. Perhaps a little more involved but still simple and very elegant. The best feature is the encoder used as the volume control itself. Really slick! I have seen encoders used in a number of Cinema processors made by Dolby...they always work very well, and allow good resolution....they also never get dirty!!! Some time this week I will work up a PCB for it, unless someone else beats me to it.
Mark
Hmmmm, digital vol control with a DAC
if you want to control all the volumes to the same level, use an audio taper potentiometer to adjust VRef of the ADC. I don't know if this is what is used in the ALEPH. <p>With a little expertise in PIC or STAMP programing you can use the Nat Semi LM197X logarithmic potentiometers for this application (well, you can do "software in solder" and use a clock/up-down counter for the same purpose of controlling the digital pot).
If you don't have a parallel out ADC, just get a 74HC595 shift register -- serial in/parallel out. -- it's about $0.60. -- use this to control the gates of a ULN2803 relay driver.
if you want to control all the volumes to the same level, use an audio taper potentiometer to adjust VRef of the ADC. I don't know if this is what is used in the ALEPH. <p>With a little expertise in PIC or STAMP programing you can use the Nat Semi LM197X logarithmic potentiometers for this application (well, you can do "software in solder" and use a clock/up-down counter for the same purpose of controlling the digital pot).
If you don't have a parallel out ADC, just get a 74HC595 shift register -- serial in/parallel out. -- it's about $0.60. -- use this to control the gates of a ULN2803 relay driver.
I am using a Digital VU circuit that I am converting to switch relays instead of LED'S. The input is normally an audio signal which is converted to DC and presented to the timing circuit as a voltage from 7 to 15 VDC. As the input rises and falls the comparator translates the input to specific thresholds and turns on or off another LED. I figured a little voltage divider(a trim Pot and divider network along with a 7807) would act as the actual volume control circuit.
As the input rises the 12 relays switch on in sequence, so instead of switching to a lower value resistor, the relays would sequentially divide down the total resistance as they remain turned on R1+R2/R1-R2. This adds the added benefit of never breaking the audio input, a sort of built in soft switch circuit. The whole thing works in reverse as you turn down the volume.
Anthony
As the input rises the 12 relays switch on in sequence, so instead of switching to a lower value resistor, the relays would sequentially divide down the total resistance as they remain turned on R1+R2/R1-R2. This adds the added benefit of never breaking the audio input, a sort of built in soft switch circuit. The whole thing works in reverse as you turn down the volume.
Anthony
Banned
Joined 2002
Actually that would probably work well. A large enough capacitor in the relay circuit to hold the relay if there is a spike or voltage drop, would take care of relays chattering and bouncingsome of that problem. It could be set up so that if there is a very bad spike the muting relay would short the output to ground. Its is simple and pretty elegant. I wonder though if the action would be lograthmic or linear???
Mark
Mark
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