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Timothy
Feleppa

I'm a mixed-signal engineer who enjoys devising elegant, innovative solutions to complex problems.

 
Here you will find some of my musings on HiFi audio, analogue circuit designs and vintage electronics.




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Latest Updates:

Tungar Power Supply

Sunday, 25th January 2026

Tungar Power Supply

This one's a quick project to put together a power supply using a couple of tungsten-argon ('Tungar') rectifier tubes.

It's a fairly primative unregulated variable DC supply design which also doubles as a variable center-tapped AC supply but primarily it's a functional display piece for the tungar tubes.

ELECTRONICS / CIRCUIT DESIGN / TUBES
Nixie Tube Clock

Monday, 19th January 2026

Nixie Tube Clock

I've designed and built a (almost) semiconductor-free nixie tube clock using IN-14 nixie display tubes and MTX-90 trigger tubes.

I delve into trigger tube ring counting circuits and devise a modular circuit design to implement a 24-hour desktop clock.

ELECTRONICS / CIRCUIT DESIGN / TUBES


Speaker Measurements: Woofers 5 to 8 inches

Tuesday, 3rd July 2018

Speaker Measurements: Woofers 5" to 8"

I've measured an initial grouping of nine 6.5"/7" woofers:
-ScanSpeak 18W/8545K00
-Usher 8945A
-SEAS CA18RNX (H1215-08 )
-Vifa NE180W-08
-Dali Ikon 6 MK1
-Fountek FW168
-Dai-ichi W6S-52
-MCM 55-5665
-Response CW2194

Some extra tests unique to this grouping have been added to evaluate bass capability and Le(x) which is a key contributor to intermodulation distortion.

SPEAKERS / AUDIO
Speaker Measurements: Fullrange/Midrange 2 to 4 inches

Thursday, 14th June 2018

Speaker Measurements: Fullrange/Midrange 2" to 4"

New measurements added:
-DLS Ultimate U2.5 (Morel CDM54) 2" Dome
-SB Acoustics SB65WBAC25-4 2.5"
-Dynavox LY302F 3.5"
-MCM Audio Select 55-5650 3.5"
-Peerless TA6FC00-04 2"

Really impressed with the Dynavox LY302F - probably the best 'full range' driver I've tested to date. The MCM 55-5650 would also make a fine midrange - and I suspect it is a close relative of the Dayton RS100 ;)

SPEAKERS / AUDIO