User manual
This is a publication by Conrad Electronic SE, Klaus-Conrad-Str. 1, D-92240 Hirschau
(www.conrad.com).
All rights including translation reserved. Reproduction by any method, e.g. photocopy, microlming,
or the capture in electronic data processing systems require the prior written approval by the editor.
Reprinting, also in part, is prohibited. This publication represent the technical status at the time of
printing.
© Copyright 2015 by Conrad Electronic SE.
Disposal
Please dispose of the product according to the relevant statutory requirements when it is no
longer used.
Technical Data
Operating voltage ........................6 - 15 V/DC (stabilised)
Current consumption ...................approx. 15 mA
Dimensions (L x W x H) ...............60 x 45 x 20 mm (ready built up assembly)
Description of the circuit
The heart of the circuit is the timer IC “NE 555”, which is connected as a multivibrator. R1, R2 and Elko C1
act as frequency-determining elements. Adjusting the speed of the chaser light happens via the trimming
potentiometer P1. Because the timer IC “NE 555” tends to oscillate very easily, the capacitor C2 is used for
its vibration suppression. The output pin 3 directly energizes the counter module 4017.
If the reset input (reset) is on “Low” (0 V), it turns the corresponding output to “High” (+ UB) on every rising
edge (junction “Low-High”) at the cycle input (pin 14); whereas all outputs which are not affected remain on
“Low” .
If in the meantime the reset input detects “High”, the element instantly resets to the numeral “zero”. In this
state the zero output is “High” and all other outputs (except “Carry Out”) are set to “Low”. After the reset input
has detected “Low”, the circulation of the chaser light starts anew.
A pivot is created when a counter output is connected to the reset input. The output 6 (pin 5) thus causes
the counter module to reset.
Since the output of the CMOS chip 4017 is not capable of feeding sufcient power to the LEDs connected,
the inverting buffer 4049 is used as the LED driver.
The resistor R3 limits the current ow through the LEDs . Since only one LED is active, only one resistor is
required for all LEDs.
Connection/Start-up
After the board has been equipped and checked for possible errors (bad solder joints, solder bridges), an
initial function test can be carried out. Proceed as follows:
• Turn the adjuster control of the trimming potentiometer on centre position, approximately.
• Place the board so that the contacts at the bottom are not in contact with any metallic surfaces, place it on
a magazine or a book, for example. Otherwise, this my cause a short circuit!
• Connect the terminal clamps marked with “+” and “-” with the correct polarity to the operating voltage
(6 - 15 V/DC). Incorrect polarity will ruin the device, the warranty will be void!
Warning!
Only a stabilized DC voltage of 6 - 15 V/DC such as a suitable power adapter, must be used for
the LED chaser light.
• The six LEDs should now light up one after the other.
• The speed of the chaser can be adjusted by turning the trimmer potentiometer.
If the function test is unsuccessful, disconnect the LED chaser light from the operating voltage.
Proceed as described in the following check list.
Check list for troubleshooting
• Is the operating voltage polarized correctly?
• Is the operating voltage 6 to 15 V/DC?
• Are the resistors soldered right?
• Are the electrolytic capacitors (Elkos) soldered with respect to correct polarity? Compare the polarity
printed on the electrolytic capacitors with the component diagram or layout diagram attached to the circuit
board. Note that depending on the brand of electrolytic capacitors “+” or “-” may be indicated on the com-
ponent!
• Are both ICs placed in the socket and is the polarity correct?
• Are all IC pins in the socket?
• Were IC2 and IC3 accidentally reversed?
• Is the LED inserted the right way round?
• Is there a ‘cold’ soldering joint? Check each solder joint thoroughly! Check using tweezers, if components
wobble. If a solder joint looks suspicious, you should solder it again for the sake of safety.
• Is there a solder bridge or a short circuit on the side of the solder? Compare conductor trace connections,
that may look like an unwanted solder bridge, with the trace image of the imprint placement and the circuit
diagram before you interrupt a circuit connection (supposed solder bridge)! In order to determine trace
connections or interruptions easier, hold the circuit board against a bright light.
• Check whether each solder point is soldered; it often happens that solder joints are overlooked.
• Always remember that a circuit board may not function, if it is soldered using soldering uid, soldering
paste or similar uxes, or when unsuitable solder is used. These materials are conductive and cause cur-
rent leakage and short circuiting.
Practical tips
• To activate the LED chaser light you may use a power adapter for example with an output voltage of
12 V/DC. If you do not want to cut off the plug, use a suitable socket, which can be connected to the LED
chaser light’s soldering pins using a piece of wire.
The LED chaser light can also be powered by a 9 V block battery.
In that case, strictly observe correct polarity; use a suitable meter, if necessary. Incorrect polarity will ruin
the device, the warranty will be void!
• The LEDs must not necessarily be soldered to the board, you may also run them by means of an exten-
sion cord (max. cable length about 30 cm). However, ensure that the contact pins of the LEDs are isolated
accordingly to prevent short circuits. For example, use heat shrink tubing that is slid over the contact pins
or a piece of insulating tape.