Parts · Opto

VTL5C6

Vactrol (LED + LDR).1 circuit uses this part. Listed as: Vactrol, fast on/fast off.

Datasheet · archived copy from Xvive; kept here as it was not found on the maker's own site

Substitutes same kind

Optocouplers and photoresistors of the same construction; the response speed and resistance range set how an effect sounds. The figures are read off each part's datasheet (this one's from page 1), typical where the sheet gives a typical value, otherwise the maximum. Closest first; the last column says what differs. A different part can change the sound, and a circuit may lean on one particular figure, so read the build document's notes before you swap.

This part

Part	On	Dark	Rise	Decay	Boards
VTL5C6	6k @ 5 mA	400k	3.5 ms	50 ms	1

Xvive 5C6 equivalent: 40 to 80 kΩ at 0.5 mA, 6 kΩ max at 5 mA, decay to 1 MΩ in about 50 ms.

Alternatives

Part	On	Dark	Rise	Decay	Boards	Differs
VTL5C9	1.5k @ 0.5 mA	2M	4 ms	50 ms	3	lower on resistance; higher dark resistance. Fast-decay vactrol (about 50 ms to 100k) suited to tremolo; this is the Xvive 5C9 sheet.
VTL5C2	10k @ 0.5 mA	2M	3.5 ms	500 ms	13	higher dark resistance; slower decay. Xvive's 5C2-R equivalent; decay to 100 kΩ takes up to 500 ms.
VTL5C3	30k @ 1 mA	10M	2.5 ms	35 ms	21	higher on resistance; higher dark resistance. Low light memory and temperature drift; the sheet prints its 10 mA and 40 mA on-resistance as 5 Ω and 1.5 Ω, almost certainly meaning kΩ.
NSL-32	500 @ 20 mA	500k	3.5 ms	500 ms	11	lower on resistance; slower decay. Slow decay (up to 500 ms to 100 kΩ), which suits optical compressors and tremolos.
VTL5C4	1.2k @ 1 mA	400M	6 ms	1500 ms	2	lower on resistance; higher dark resistance; slower decay. Very low on-resistance (125 Ω at 10 mA) but a slow decay of up to 1.5 s.

Faceplate	Circuit	Based on	Category	Vendor	Box	Knobs	Price	BOM
	Polyphemus Optical Compressor 4558 · 741 · LM741 · LT1054 Pigtronix Philosopher's Tone · 125B	Pigtronix Philosopher's Tone	Overdrive	Aion FX	125B	5	$12.50	79