Archive for the Category


AC Load Line Power Flasher by SCR

Tuesday, June 24th, 2008


Here is an unusual flasher circuit for 120VAC loads. The circuit is similar to the two-transistor flasher seen in several circuits in techlib.com except that an SCR is used.
A little circuit trick is hiding in the selection of the 0.1uF capacitor in series with the 1k resistor. When the SCR is off, this capacitor smoothes [...]

Sequential Flasher Christmas light strings by SCR

Thursday, June 19th, 2008


Here is a simple circuit for sequentially flashing Christmas light strings or other similar low-power lamps. The socket symbols may be single bulbs or sockets for lamp strings. The load must be capable of operating from DC since the SCRs rectify the line voltage. The SCRs must be sensitive-gate types and must be able to [...]

LINEAR CONSTANT CURRENT White LED Dimmer

Friday, June 13th, 2008


This simple Linear circuit provides continuously variable regulated current (~25-400mA) from a 4-6 Volt source. I chose a linear design for simplicity, reliability, ease of repair, and to avoid switching EMI in my Cave Radios. The circuit requires only 0.2V headroom above the parallel LED Array voltage to provide regulation at [...]