NLC DP Filter - Build notes.

Th Nonlinearcircuits DP Filter is a really interesting beast.
It takes ideas from the TB303 & Moog ladder and combines this with the EMS Diode ladder.
(The TB303 is a four stage diode ladder filter achieved with transistors where the collectors are connected to base. The Moog is a straight transistor ladder filter).

This DP circuit replaces the diodes and transistors of these 3 ladder filters with opto-isolators

Opto-isolators (also called optical couplers or optocouplers) are basically a LED & a photo transistor in a light tight package. They use light to transfer electrical signals between circuits to keep them electrically isolated from each other. In this module the TLP521-2 is used.

Andrew's Build notes are here:
http://www.sdiy.org/pinky/data/Double%20Penetration%20Filter%20build%20notes.pdf

    More useful links:
1. Large schematic
2. Module description.
3. Muffs thread
4. NLC blog - pics of the module

 This module is probably not the easiest one to start with if you are a beginner.
There are lots of surface mounted components, though on the bright side there is only one SMD IC.
(a 074).

I like to get the ICs out of the way so I'll solder the 074 first then the rest of the caps & resistors

 The back side of the PCB also has SMDs. It's not the cleanest of  SMD soldering efforts but should still work. Fingers crossed.

There are two SMD pads marked "c" on the rear side of the PCB....They are for 100k resistors.
Also, I'm using 0805 sized SMD components (its what I had in my store). The pads on this PCB are sized
1206. If you are using smaller ones like me, be careful when soldering the capacitors - let them cool down before soldering the other pad.

There are 2 versions of this filter - the standard using 100nF for C2,C3,C4 & C5 vs the TB-303
acid version which uses a 33nF on C2,C3,C4 & a 18nF on C5.

I'm building the standard version today.... all 100nF.(104).


The trannies next. Six BC547, and two BC557s.
I didn't bother to match these.

The 2 caps marked C22 & C23 near the power connection are 10uF electros.

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