That is a very nice relay with great specs.
Zero crossing in something like a PGA2311 is easier to do since internally they use analog switches which can be made to switch A LOT faster than mechanical relays and their switching time is much more predictable than mechanical relays.
Regarding using SSR instead of relays, it could probably work but then you have to think about distortion, while relays and good qualtiy resistor are more or less free from distortion.
You could also use CMOS switches instead of relays but then again you have the issue of distortion since CMOS switches are not distortion free.
Everything is a compromise.
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Nearly a year has passed since I made V2 available.
I am now very close to being done with V3, schematic has been finished, layout is finished, gerbers have been made and PCB's are in the process of being manufactured.
If all goes well I should have something to show during the first half of April.
V3 includes :
1. A few Bugfixes(no board level modifications are needed on V3)
2. Improvements(external on-board clock source instead of built in oscillator in ADC0804)
3. Simplification(the detent function that stabilizes the circuit by using the LSB has been made simpler)
4. Expandability(stackable expander board(s))
Board size stays the same, number of steps is the same, step size is the same.
I am now very close to being done with V3, schematic has been finished, layout is finished, gerbers have been made and PCB's are in the process of being manufactured.
If all goes well I should have something to show during the first half of April.
V3 includes :
1. A few Bugfixes(no board level modifications are needed on V3)
2. Improvements(external on-board clock source instead of built in oscillator in ADC0804)
3. Simplification(the detent function that stabilizes the circuit by using the LSB has been made simpler)
4. Expandability(stackable expander board(s))
Board size stays the same, number of steps is the same, step size is the same.
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I know I promised that I would have something to show in the beginning of April.
However, it turns out a critical component is out of stock at both Mouser and Digikey.
I checked the delivery time on Mouser.com and they should have some in stock May 1, Digikey.com should have it in stock May 3.
So it will still be 5-6 more weeks from now.
Sorry.
However, it turns out a critical component is out of stock at both Mouser and Digikey.
I checked the delivery time on Mouser.com and they should have some in stock May 1, Digikey.com should have it in stock May 3.
So it will still be 5-6 more weeks from now.
Sorry.
You can add an expander board, that can be stacked on top of the main attenuator board. That will give you control of 4 channels with a single pot.
That is enough for attenuation of a balanced/differential signal.
V3 is designed for stacking up to 3 expander boards on top of the main attenuator board.
Main attenuator board + 3 expander boards = control of 8 channels with a single pot.
I have not ordered any expander boards since I do not need it for my own projects but if there is enough interest I might order a small batch.
I know I promised that I would have something to show in the beginning of April.
However, it turns out a critical component is out of stock at both Mouser and Digikey.
I checked the delivery time on Mouser.com and they should have some in stock May 1, Digikey.com should have it in stock May 3.
So it will still be 5-6 more weeks from now.
Sorry.
That 1 critical component with no second source? It is back in stock 2 weeks early. Great.
But then there were 3 other components that were out of stock, and 1 of them would only be back in stock sometime in October/November.
However, those 3 components were not critical and I was able to find suitable substitutes for them.
What this means is that components have been ordered from Mouser and if I am lucky and receive them soon I *should* have something to show on Saturday/Sunday if all goes well.
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I take it the step size could easily enough be changed using the relay calculator here: Logarithmic Attenuator Calculator?
If you do get the expansion boards made I would certainly be interested in a main board plus an expansion board so as to attenuate a balanced signal.
If you do get the expansion boards made I would certainly be interested in a main board plus an expansion board so as to attenuate a balanced signal.
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That is the calculator I have used.
So it is not hard to calculate another step size if the standard 0.6dB step size is too high or low.
Update on progress :
Mouser has been pretty slow to ship my order. I placed my order Saturday night and Mouser still hasn't shipped my order.
Mouser shows my order to be "In Shipping" so it should ship today.
This means that I have to postpone assembly of my first V3 PCB until next week.
I will only offer blank boards.
I only offer boards to pay for my own hobby projects, offering assembled boards would make it more like a business instead of a hobby.
I like to keep it as simple as possible for me.
So no plans for assembled boards, but if someone wanted to buy 50+ assembled boards from me I could proably arrange something. But that is not likely to happen.
I am using Bit 2-8 for the 7 relays. Bit 1(LSB) is used to stabilise the circuit, there is a small circuit attached to the output Bit 1(LSB) and this small circuit can either add or subtract 1/2 LSB. The bottom of the potentiometer is atttached to the output of this circuit.
It is simple but very effective, been using my V2 attenuator for about a year without issues.
The same principle is used in V3, however it has been simplified a little, but it will perform the same function.
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