This board would permit any brands of tube amplifier to warm up vacuum tube filament first, then switch to high plate voltage in about - 40 to 80 seconds later. Research shows that without proper warm up, vacuum tubes would decrease life span significantly (instead of 5-7 years of normal life span in average home use, power tubes would wear out within 1-2 years in most situations). That is the reason why most tube amp makers would only offer 6 month warranty on tubes.
To protect your expensive output vacuum tubes such as 300B/2A3/845, KT88/El34/KT66/6550 ... to achieve longer lifespan of these expensive tubes, you need to get this delay action board (assembled, ready for use). The board would pay for itself 10-20 times within 12 month in use by saving on the direct heated triode output tube (300B/2A3/45) and KT88 lifespan, or 5 times cost saving on El34/6L6/6V6/El84 tubes.
The board is only powered by the secondary of the high voltage transformer, no need to add extra supply, makes it also very simple to connect Very reliable as no mechanical relay is used.
A led lamp will light when high voltage is delivered to the load.
Dimensions : 90 x 50 x 20 mm
Maximum input voltage: 450 Volts
Maximum switched current: 2 Ampères
Nominal delay : 40 à 80 seconds adjustable by 10 turns trimmer
Longer delays available by adding one tantalum capacitor
Max. current drawn by the board : < 10 mA from a.c. side of the high voltage transformer