HEY ! . . . . . Sir . . . . . " Solanum tuberosum " man . . . . .
0% all pure theory . . . . . 100% all factual / functional reality . . . . and faultlessly working from 1946-2019 . . . to date, as the flashing
POWER ON indicator on my self assembled isolation transformer + a following VARIAC in its metal enclosure.
So that makes about 73 years of brilliant ORANGE blinky-blinky action . . . whenever so called upon, by a
POWER ON condition .
It consists merely of a rectifier diode feeding into a small carbon . . . voltage dropping / current limiting resistor that then feeds into a paper / poly capacitor shunting across a NE-2 neon lamp.
( A NE-51 version was used back in my construction days, since the mini all glass blob, leaded NE-2 had not yet come upon the scene.)
The + nodes of the AC gets rectified to DC and then is voltage dropped to charge the cap that is shunting the neon lamp.
Upon power up, the reduced DC voltage flows directly to the capacitor and startes charging it up.
When it builds up an ~ 72-75 VDC level, where the threshold of ionization of the neon lamp is met, the lamp electrodes flashover from that stored level of charge within the capacitor.
There is one brilliant orange flash, then the charge depleted capacitor starts a recharge to repeat that same timing cycle.
You sort of have to evaluate the flash intensity and up the capacitance if you want a brighter flash and make a like decrease in the resistance of the resistor to get a quicker charge time , if the chosen capacitance value was raised.
I remember experimenting, using .47----.68 ---- and 1 ufd caps with accordingly selected dropping resistors.
I finally got my result of a bright orange flash every 2 seconds.
Joe Blow and Colloqial Local Yokels can find neon lamps within the storage drawers of the electrical section of a FULL SERVICE . . . . . ACE Hardware store.
Its circuit look-a-like dis . . . .
On a droppable item like a glue gun, one might additionally place a clear plastic cover over the exposed lamp portion.
73's de Edd . . . . .
What has four legs and an arm? . . . . . . . . . . . . . . one HAPPY pit bull.