Distinct Federal Wail Characteristic 60's 70's & Maybe 80's

[TitleXIII]

Can anyone here tell me why a Federal Signal PA-15, PA-20, PA-70 and PA170 would briefly ramp down when switched from YELP to WAIL?

These seem to be the only make/model of sirens that do that.

Thanks to any and all who reply!

 

[toon80]

Member Wailer should be able to help you out on that.

 

[Wailer]

The Federal PA15A series 1E, PA20A series 2E, PA70, PA100, PA150, PA170, PA200, and PA1000 all share the same siren oscillator circuit. The circuit was introduced in the early 1970s and is designed to produce high-pitched wail and yelp tones like the sirens we hear nowadays. I call it the 'screamer circuit' because the wail tone sounds like a two year old child throwing a nasty temper tantrum.

The sound you are describing is sometimes called the 'bomb drop' and usually occurs when flipping the selector switch from yelp back to wail. I think that may have something to do with the configuration of the diodes and capacitors in that type of circuit. If you move the switch in between the wail and yelp tones you will also get a 'chirping' sound, and if the siren has the hi-lo tone you get a weird 'barking' tone between yelp and hi-lo.

 

[TitleXIII]

Thank you Wailer for the explanation.

When I first started upfitting vehicles, I can remember a bunch of PA15 sirens going to the dumpster. I can't believe the amount of money people are asking for them on eBay. Wish I had kept them!

 

[Wailer]

Thank you Wailer for the explanation.

When I first started upfitting vehicles, I can remember a bunch of PA15 sirens going to the dumpster. I can't believe the amount of money people are asking for them on eBay. Wish I had kept them!

What you probably saw were a bunch of PA15A series 1Es. That is the most common version.

Regarding eBay, I can't believe how much people are asking for anything that is used and out of production. A lot of sellers think they have valuable collectors' items and want to fetch top dollar for them.

I have two 1970s era Federal electronic sirens with the screamer circuit. A PA20A series 2E and a PA200. Of the two, I think the PA200 is a much better siren in terms of build quality. It doesn't rattle when I shake it and the circuit board is removable for ease of maintenance. It also has three power options: 58 watts with one 58 watt speaker, 100 watts with two 58 watt speakers, and 200 watts with two 100 watt speakers.