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[TowerTalk] 300 MHz Remote Switch

To: TowerTalk <>
Subject: [TowerTalk] 300 MHz Remote Switch
From: Pete Smith <>
Date: Thu, 22 Dec 2011 08:26:56 -0500
List-post: <">>
Thanks to everyone who responded to my message recently about this 
device.  I've done a bit more reverse-engineering/testing, and thought 
the result might be of interest.  If the following writeup is 
uninteresting, click Delete now, and Merry Christmas to everyone.

_All About the CDKZQ-8L Remote Switch_

This unit is a very inexpensive 8-relay remote switch.It uses a 315-MHz 
radio link between the battery-powered controller and the receiver, and 
each of its 8 relays is rated to handle 20 amps at either 14 VDC or 125 VAC.

The controller has 8 buttons.The first two are larger, but all appear to 
operate identically, except when programming (see below).

You must take the receiver unit out of its plastic case to program 
it.Once you have done so, place the receiver unit so that the 
programming button and its associated LED are at the lower right.The 
eight relays are arranged like the pins on an IC, and their numbering 
follows this convention.Hence, relay 1 is at the upper left, relay 4 at 
the lower left, relay 5 at the lower right, and relay 8 at the upper right.

Each relay is SPDT/normally open, and three terminals are available for 
the user, labeled A, B, and C.B is the common terminal, A is the 
normally open side of the relay, and C is the normally closed side.

The receiver unit requires 12V DC.DC is supplied to the 2-terminal strip 
at the top center of the unit, when positioned as above.The strip is not 
marked, but the terminal nearest the large diode next to it is "+";the 
diode will keep you from making a mistake, by blocking voltage from the 
unit if you connect it incorrectly.  One spec sheet suggests that this 
diode may also enable it to be powered by 12 VAC.  I have not tried this.

The current drawn depends on the operating mode and, in 
latching/non-interlocked mode, on the number of relays activated 
simultaneously.With just the receiver operating, the unit draws 5.6 mA.A 
single relay raises that to approximately 56 mA, and each additional 
relay adds about 50 mA.


The receiver/relay unit can be programmed to operate in one of three modes:

1.Latching -- press a button, and the corresponding relay is energized, 
and stays energized until the button is pressed again.

2.Non-latching (momentary) -- press a button, and the corresponding 
relay is energized so long as the button is pressed.Release the button, 
and the relay is de-energized.

3.Interlocking -- press a button, and the correspondingrelay is 
energized until another button is pushed.

Programming is very simple.Momentarily press the programming button on 
the receiver unit.The LED next to it will light.Then press the button on 
the controller corresponding to the mode you want, as numbered above.The 
LED will flash quickly a number of times, indicating that the receiver 
has been programmed.To clear the programming and return the unit to its 
original state, press the programming button again.

73, Pete N4ZR

The World Contest Station Database, updated daily at
The Reverse Beacon Network at, blog at,
spots at, port 7000 AND now
at port 7000


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