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The FET, sometimes called JFET, used in the filter on the main board is the somewhat hard to get
J201. Mouser sell them as their part 106-J201. I should warn you they aren't terribly cheap
compared with other small signal FETs.
The small positive temperature coefficient (PTC) resistor used in the filter is +3300ppm/K,
al3000ppm/K devices will do the job well enough too.
The two large PTC resistors used on the VCO board are wirewound 1K +3500ppm/K types and are
made by KRL. Their part number is C-2AQ.
The AS3310 used on the main board are envelope generators and are made by Alfa in Latvia. The
AS3310 is a clone of the much older and now obsolete CEM3310 chip. You can use either the
CEM3310 or the AS3310 in the ASV. However, if you use the CEM3310 you should make R154
and R157 both 24K. The CEM3310 has a typical maximum attack peak voltage (Vp) of 5.0V. Early
specimens of the AS3310 have a Vp of more than this. I have tested several devices and all were
showing a Vp of 5.4V. Because of this I have made R133 and R148 on the main board to be both
36K. This increases the maximum sustain voltage to 5.2V to reduce the small discrepancy with the
maximum sustain level and the slighter higher than expected maximum attack voltage. Ideally there
should be no discrepancy but 5.2V seems a good compromise between the expected value of 5.0V
and the measured value of Vp in some real devices. Alfa's Alex Zaslavski told me in November
2018 that this has been corrected and Vp will be closer to 5.0V for all new productions of the chip.
The AS3310 you purchase, and indeed any CEM3310 you have, may well have a Vp of 5.0V and
you can use 39K for R133 and R148. However, using 36K as shown in the parts list will allow
perfectly acceptable performance for both versions of the AS3310, and the original CEM3310.
The board interconnects used to connect the main board with the pot board, and the main board with
the VCO board, are in two parts, the male header and the female socket or receptacle. All of these
interconnects are ten way single in line (SIL) connectors. The ones I have used in my builds are
made by Multicomp, although more expensive types are available which may offer increased
longevity. These are the Multicomp part numbers for the parts I used:
10 way socket
2212S-10SG-85
10 way header
2211S-10G
With the above headers I found the resistance to movement sufficiently stiff that the whole three
board assembly stays together without additional mounting support. However, if you are planning
to travel with your ASV then I do suggest using the four suitable M3 hex spacers, nuts and screws
to secure the unit together.
For the Multicomp headers above I needed 11mm spacers plus a flat washer to fit the three boards
together without stressing them. The 11mm M3 male-female hex spacers are made by Harwin, their
part number R30-3001102.
The trimmers used in this project are 6mm and multiturn types. The 6mm ones are Bourns 3386F
types, and the multiturn ones are Bourns 3296W. Other manufacturers make similar products but be
sure to check the pin spacing will fit the PCBs.
The 1/4” sockets on the socket board are Switchcraft 112APCX. These are excellent parts and will
last a long time. However, quality does come at a price and they are not cheap.
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