Jack Hammer Instruction Manual

Thank you for your purchase of the Powercall “Jack Hammer” Low Frequency Siren add-on. You’ve now purchased a “Fierstien Brand” Powercall Emergency Siren product.  Always ask for it by name!

Operating the Jack Hammer is self explanatory once connected properly.

1)  The unit is triggered by a POSITIVE  PULSE ONLY.  Each time the unit is given a momentary positive pulse, the Jack Hammer unit will activate, for the time chosen via the potentiometer on the unit. You can run your Jack Hammer
anywhere from 8 seconds up to 60 seconds before the unit will reset.
Follow the diagram above to set the time for your Jack Hammer. As an example, if you are setting the unit for 15 seconds, LIGHT #1 will be on when you turn the blue dial. 60 seconds would be all 3 lights on etc. It’s self explanatory.
Once the timer runs out, just give the unit another positive signal hit and the unit will start up once again.

The wiring on the Jack Hammer is as follows:

RED WIRE with fuse goes to Power. I recommend putting power on a switched ignition source so the unit is not on 24/7.

BLACK WIRE goes to a good ground source. Make sure you scrape any paint
and primer away from your ground source and use a star washer!

BROWN/WHITE ZIP CORD goes directly to the Jack Hammer module. There is no polarity necessary.

GREEN/WHITE ZIP CORD goes in between one of your SIREN SPEAKERS leads. Cut one of your siren speaker leads in half and place the green and green/white wire on each end of one.

BROWN WIRE gets tied in to the other siren speaker lead. DO NOT CUT THIS LEAD, just tie into the lead via splice. (NO SCOTCH LOCKS).

WHITE WIRE is your TRIGGER WIRE. Give this wire a QUICK POSITIVE PULSE and that will activate the Jack hammer module.
*Sound output: 120 dB
*Frequency: 450-1500HZ
*Size of speaker: 6.9" in
Diameter x 8.5" Tall
*100 Watt speaker
*Weight: 8.5lbs

This unit adds a low frequency subwoofer sound to any 100 watt siren you tie it to, helping to “Shake the Ground” so other people driving hear you or “Feel the siren” sooner, moving them out of the way quicker than conventional units.

This unit was built and designed by David Fierstien of Powercall Sirens.
Contact me for any questions at 703-669-1193.

The unit comes with the Jack Hammer unit, the amplifier box and general wiring.





Operating the Siren is self explanatory, with the exception of a few items:
1)USB Selector—Plug a USB Flash drive into your siren that has AN MP3 sound file and the unit will amplify that sound. The file MUST BE AN MP3 FORMAT.

2) The volume knob controls THE ENTIRE SIREN. So if your volume knob is down, the siren volume will be down as well. This is especially helpful when using the USB function during parades, Santa rides and other special events when you don’t want the siren to be full blast!

3) The intersection mode OVERRIDES everything. If your intersection mode is on, press the intersection button again to shut it off. 4)All other functions are self explanatory.


SPK1 AND SPK1—Connect these terminals to one speaker only. The polarity generally doesn’t matter and you will do no damage by hooking them up backwards. Your speaker should be 11ohm. (See speaker note enclosed in this siren packet)

White - This unit will rotate through all the tones on the UDX7 by giving this terminal a quick negative pulse.

+ Hook this wire to a fused 12V power source. The unit has an internal 20 amp fuse. You are welcome to install an additional fuse holder if needed. Please DO NOT use more than a 20 Amp fuse. We DO NOT recommend using a fuse block for your siren unless the block is made for that purpose. Ensure your power is a good, strong power source or the unit may not function properly.

- Ground, Hook this terminal to a STRONG grounds source. Ensure there is no primer or paint on this source. We recommend using star washer to ensure a good ground point. Bad ground will cause the unit to not function properly.

- N/A—This terminal is NOT USED.

- SPK2 AND SPK2—Hook these terminals to a 2nd speaker if you are using dual speakers. If you are using one speaker, you can use either the SPK1 or the SPK2 terminals. DO NOT CROSS THESE TERMINALS.


If you are replacing your siren with one of ours, IT IS IMPERATIVE that you check your existing speaker wiring to ensure it’s wired correctly. Failure to do so could damage your siren beyond repair. Contact us for any questions. Feel free to contact David Fierstien for installation questions at 703-669-1193 or via text at 703-955-6547 M-F from 8AM to 5PM.

If your Powercall has a problem, you have damaged the siren or it needs service, please do the following:

1) Write or type out an explain of what the problem is, what type of siren you have and what may or may not be working. You can also visit our website under the repairs/warranty tab and get these complete instructions for returning units.

2) Package your unit up GOOD so it does not get damaged in shipment. Powercall Sirens IS NOT responsible for damage done to your unit due to incorrect packaging.  We will require your full name, company name, shipping address, phone number and an email address, as well as a detailed description of what the problem is with your unit. This information MUST be included In your shipment.

3) Once we receive your siren, we will contact you with what we find and any
possible costs involved in fixing it.

Powercall Sirens #1 speaker recommendation for our sirens is Powercall 6DX siren speaker. The magnet on a speaker is what requires the most cooling when the siren is in operation. Customers and manufacturers who put "Behind the Grill" or "Concealed" speakers behind steel bumpers, sometimes don't realize that when they do that, the back of the speaker (The magnet) does not get cooled since it is blocked by the bumper. This can hamper the life of your speaker and cause it to blow due to lack of cooling. This is why our 6DX comes with the speaker magnet facing forward, to optimize cooling and give you longer life, higher quality siren driver.

The 6DX speaker is the #1 recommended speaker for all of our Powercall Sirens. It’s a very inexpensive speaker, starting at $99.99 and is available on our website for immediate purchase. Feel free to contact us for any questions.

Powercall Sirens LLC
708 Sentinel Drive NE
Leesburg, VA 20176
Direct: 703-669-1193
Text: 703-955-6547