Autoranger for soundcards

gpapag

Moderator
Paid Member
2002-11-17 6:42 pm
Athens-Greece
A full weekend for me to assemble this beauty :wave:

George
 

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gpapag

Moderator
Paid Member
2002-11-17 6:42 pm
Athens-Greece
Thank you all for dropping in.
Jan, a great kit construction wise. Not a novice level’s but a proper work. Can’t be done in one go. It requires taking some breaks in between, plus checking and double checking (*).
Where did you find all the parts? They are not currently available.
Jan made the right decision to include Mouser P/Ns in his BOM spreadsheets. So I compiled them into Mouser format spreadsheets -only up to 30 component P/Ns each- and gave the order (**).
They reported receipt dates of the backlogged items (a few resistors and some test pads, to be received some months from now) so I asked them to ship what they already had in their stores and regarding the backlogged items to be shipped when they will all be available.
I was corresponding with Italy, the goods were shipped from Texas. Fedex through Memphis, Paris, Koeln, to my hands in Greece. Less than 4 days from order placement to doorbell ringing.

I have replaced the missing 1% resistors with single or two in series resistors selected and tested with a Der EE-5000 LCR for well within 1% limits.

I hope it functions as nicely as it looks.
I have done no functional tests yet. The real fun is ahead

George

(*) did I mention that the USB connector of the Silent Switcher has to be mounted at the component side? :(:D
(**)I was not very successful with the compilation and I placed a few components in two spreadsheets so I ordered those twice and I missed ordering one (failed to double check due to enthusiasm, like a little school girl Sonny Boy Williamson I - Good Morning Little SchoolGirl - YouTube ).
 

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gpapag

Moderator
Paid Member
2002-11-17 6:42 pm
Athens-Greece
I think I mention the location of the USB connector, or at least in a pic.

Jan, you make a proper notice of the location in the assembly instructions and you do it in bold letters plus a picture :up: .
I mentioned it to emphasize my stupidity. (I think I qualify as a beta tester for a "foolproof" assembly design :D)

The several caps you highlighted have their designator on the top board, and you can't see that anymore after you place the connectors. My bad, sorry.

Designators become obvious following the BOM. Even I placed them properly :)

George

>Edit. Jan, there are two LEDs on the main board. D7 (green) and D8 (red) which both lit. Is this OK? Are they biasing elements?
 

gpapag

Moderator
Paid Member
2002-11-17 6:42 pm
Athens-Greece
The IC that I missed ordering was ADA4610-2 ( U3 on attenuation board)
I have in my drawers some FET input dual opamps (TL072, TL082, LF412, OPA2134) and I asked Jan if I could use one of those for U3. He said they can be used and suggested to go for lowest DC offset. I soldered an 8 DIL socket and started testing the (15 total) ICs.
I probed at pin 1 of U3 ( junction of R8 &R30 is easier to probe) with no input signal (“SE”, “+18dB” on the display). I let half a minute after switch on for voltage variation to settle down. See DC offset voltages and corresponding display “Vi” and “Vo” values.
I installed the TL082 with the 4mV DC offset (rock stable and a tad lower after two hours idle).
I also bridged JP6, JP7 (another of Jan’s belt and suspenders), changed the nominal output level of the Autoranger to 0.5Vrms and I am ready to go.

George
 

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Dear friends,
In the past several of you have expressed interest in my autoranger, which has been sold out for some time now. I am happy to say that I have ordered more cases and PCBs. Due to material shortages new autorangers will be available in september. I will have about a dozen silentswitchers so will be able to assemble a dozen halfkits as noted on the linearaudio.nl website:

lettered, painted, punched and studded enclosure;
programmed controller;
attenuator PCB with the LT1968 presoldered;
display/control PCB;
fully assembled silentswitcher power supply.

Price will be as the initial one, € 149 + shipping.
I will come back once I have them ready to ship, but if you want to reserve a unit, please prepay € 50 to [email protected] if you want to be sure to get one.

Jan