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Assembly and Operation Manual

CPO1 Code Practice Oscillator Kit

WWW.AB5CW.COM Rev. C

CPO1 Code Practice Oscillator Kit - Assembly and Operation Manual of 18

IMPORTANT The builder is advised to read this entire

manual prior to beginning assembly.


Introduction The CPO1 Code Practice Oscillator Kit produces a sine-wave audio tone that is ideal for practicing Morse code. The frequency is adjustable between approximately 550 Hz to 1100 Hz (actual frequencies may vary due to component tolerances, battery voltage, etc.). The on board audio amplifier provides more than enough power to drive either common stereo headphones (monophonically) or a user supplied speaker. The volume is adjusted by potentiometer R12. The key connector (J2) is a standard 3.5mm stereo jack and will accept either a stereo or mono 3.5mm phone plug. The oscillator is keyed by connecting the tip connection of J2 to common (the sleeve of J2). The audio output connector (J3) is a standard 3.5mm stereo jack with tip and ring connected together. When used with stereo headphones the audio tone will appear in each earpiece as a monophonic signal. There are pads provided (J4) for the connection of a user supplied speaker. The speaker is taken out of circuit (silenced) when the headphones are plugged into the audio output connector (J3). Test points labeled TP1 through TP7 are placed at various locations on the PC board to assist in troubleshooting. Refer to the schematic on page 18 of this manual for test point specific locations.

IMPORTANT

Some of the devices in this kit can be permanently damaged by static discharge. It is recommended that this kit be assembled on a properly grounded anti-static work

surface and that other anti-static procedures such as a properly installed wrist strap and a grounded tip soldering iron be used during assembly.

CAUTION

Some of the devices in this kit, as well as the solder used to assemble it, may contain lead. Lead is a hazardous substance. Work in a well-ventilated area and

wash your hands thoroughly prior to eating or drinking.


Tools Required The following tools are required (supplied by the builder) to assemble the CPO1 Code Practice Oscillator:

- Temperature controlled soldering iron - .5mm (.020”) to .8mm (.032”) diameter rosin core solder intended for the assembly of

electronics. - Small wire cutters - Small Phillips screwdriver - Small needle nose pliers - Magnifying glass (to read markings on small parts)

Accessories Required The builder will need to supply the following accessories in order to use the CPO1:

- Telegraph key - Cable with a 3.5mm (stereo or mono) plug to connect the key - Stereo headphones (the CPO1 produces monophonic sound in each earpiece) - 9V battery (Alkaline is recommended) - 8 to 16 ohm speaker (if desired)

A Note About Soldering Although assembly of this kit is fairly straight forward, it is important that anyone assembling this kit knows how to properly solder electronic components. Poor solder technique can result in damage to components and a damaged and non-working product. It is beyond the scope of this manual to teach proper soldering techniques for electronics. If the builder is not experienced in the processes and hazards associated with soldering electronic components they should seek the guidance of someone who is prior to beginning construction of this kit.

SAFETY Wear safety glasses when assembling this kit.

- Cut leads can sometimes fly off in unexpected directions. - Molten solder can pop or splash unexpectedly. - You are only allotted one set of eyes.

Hazards associated with soldering include (but are not limited to):

- Severe burns caused by the soldering iron. - Risk of fire. - Fumes from the melting solder. - Lead in the solder. Lead is a hazardous substance.


This Parts List is a complete listing of everything included in the kit.

It is wise to take a complete inventory of the kit by comparing each part with the Parts List before beginning assembly.

Parts List ITEM QTY PART NO. DESCRIPTION REFERENCE

1 1 1000748 PCB, CPO1 CODE PRACTICE OSCILLATOR

2 1 1000768 RESISTOR, 1.8K, 1/4W, 1%, MF (BRN/GRY/BLK/BRN/BRN) R10

3 1 1000600 RESISTOR, 10, 1/4W, 1%, MF (BRN/BLK/BLK/GLD/BRN) R11

4 2 1000889 RESISTOR, 18K, 1/4W, 1%, MF (BRN/GRY/BLK/RED/BRN) R3, R4

5 2 1000592 RESISTOR, 1K, 1/4W, 1%, MF (BRN/BLK/BLK/BRN/BRN) R1, R7

6 2 1000773 RESISTOR, 39K, 1/4W, 1%, MF (ORN/WHT/BLK/RED/BRN) R8, R9

7 2 1000805 RESISTOR, 6.8K, 1/4W, 1%, MF (BLU/GRY/BLK/BRN/BRN) R5, R6

8 3 1000500 CAPACITOR, 100nF, 50V, X7R MLCC (MARKED 104) C3, C4, C7

9 2 1000633 CAPACITOR, 10nF, 50V, X7R MLCC (MARKED 103) C1, C2

10 1 1000762 CAPACITOR, 47nF, 50V, X7R MLCC (MARKED 473) C9

11 1 1000753 DIODE, 1N4007 D1

12 1 1000770 SLIDE SWITCH, SPDT, RIGHT ANGLE SW1

13 2 1000664 AUDIO JACK, 3.5MM STEREO J2, J3

14 1 1000608 SOCKET, 8 PIN, DIP (U1)

15 2 1000747 TRANSISTOR, 2N3904, TO92 Q1, Q2

16 1 1000549 POTENTIOMETER, 10K, LINEAR R2

17 1 1000759 LED, GRN, T-1, 3MM, 2mA D2

18 2 1000775 CAPACITOR, ELECTROLYTIC, 10uF, 25V C5, C6

19 1 1000752 CAPACITOR, ELECTROLYTIC, 100uF, 25V C8

20 1 1000896 POTENTIOMETER, 10K, AUDIO R12

21 1 1000757 BATTERY SNAP, 9V J1

22 1 1000907 IC, NJM386 AUDIO AMPLIFIER, DIP-8 U1

23 1 1000756 BATTERY HOLDER, 9V BT1

24 2 1000899 SCREW, M2 X 4MM

25 2 1000900 NUT, M2 HEX

26 4 1000901 SCREW, M3 X 10MM, NYLON

27 4 1000902 NUT, M3 HEX, NYLON

It is recommended that the builder install one component at a time. This means that each component should be inserted, soldered, and the leads trimmed as shown on the following page, prior to installing the next component.


Assembly The builder is advised to read through this entire manual prior to beginning assembly. This manual assumes that the builder is familiar with the soldering process and the hazards inherent in soldering electronic components. If this is not the case, the builder is advised to seek competent guidance before proceeding further. Unless otherwise instructed, all components should be installed onto the top side (the side with the white component outlines) of the printed circuit board. Unless otherwise specified, the word “install,” when used in an assembly step, means the leads of the component are formed to match the holes in the PCB (if required), the component is properly positioned, the component leads are properly soldered, and (unless otherwise instructed) the protruding leads are trimmed. Refer to Figure 1 for an illustration of a properly installed component (a resistor is shown as an example).

It is critical that electrolytic capacitors are installed with the proper polarity. Incorrect installation of an electrolytic capacitor can result in the destruction of the capacitor when power is applied to the circuit. Refer to Figure 2 for installation of electrolytic capacitors.

Figure 1

Proper Component Installation

Figure 2 Electrolytic Capacitor Installation


Use only high quality rosin core solder intended for the assembly of electronics. Either tin/lead or lead free solder may be used to assemble this kit. 0.5mm to 0.8mm (.020” to .032”) diameter solder is suggested with 0.5mm (.020”) diameter recommended. The use of a good quality, temperature controlled soldering iron is recommended.

Assembly should proceed in a step by step manner with the builder checking off each item as it is completed. The parts will be installed in the order that they appear in the Parts List on page 5 of this manual.

Install one component at a time. This means that each component should be inserted, soldered, and the leads trimmed, prior to installing the next component. Check off each item as it is completed by placing a check mark between the parentheses ( ).

Step 1 ( ) Position the PCB (Item 1) on the work surface, oriented as shown in the illustration below, with

the white labeling facing up. Unless explicitly stated otherwise, all components will be installed on the top side of the PCB (the side with the white labeling).

The resistors are installed first. All of the resistor patterns on the PCB have a 10mm (.4”) lead spacing. Resistors do not have a polarity so it does not matter in which orientation they are installed.

Note: Save the cut off leads from the next step (Step 2). They will be used to form the test point loops in Step 5.


Step 2

Install the following resistors: Save the leads that are cut off in this step. They will be used to form the test point loops called for in Step 5. ( ) R10 1.8k BROWN / GREY / BLACK / BROWN / BROWN ( ) R11 10 BROWN / BLACK / BLACK / GOLD / BROWN ( ) R3 18k BROWN / GREY / BLACK / RED / BROWN ( ) R4 18k BROWN / GREY / BLACK / RED / BROWN ( ) R1 1k BROWN / BLACK / BLACK / BROWN / BROWN ( ) R7 1k BROWN / BLACK / BLACK / BROWN / BROWN ( ) R8 39k ORANGE / WHITE / BLACK / RED / BROWN ( ) R9 39k ORANGE / WHITE / BLACK / RED / BROWN ( ) R5 6.8k BLUE / GREY / BLACK / BROWN / BROWN ( ) R6 6.8k BLUE / GREY / BLACK / BROWN / BROWN Next, the ceramic capacitors are installed. The ceramic capacitors may be either yellow, blue, or red in color. Their values are printed on their side. It helps to have a magnifying glass in order to read them.

Step 3

Install the following ceramic capacitors: ( ) C3 100nF 104 ( ) C4 100nF 104 ( ) C7 100nF 104 ( ) C1 10nF 103 ( ) C2 10nF 103 ( ) C9 47nF 473

Step 4

Install the polarity protection diode. This component must be installed in a specific orientation. Note that the component outline for D1 on the PC Board is a rectangle with a bar at one end. This represents the location of the cathode of the diode. The diode itself has a black body with a white ring around one end which identifies the cathode. The white ring on the diode must be oriented in the same direction as the white bar on the PC board. ( ) D1 1N4007


Step 5 Install test points. This step uses the cutoff leads from previously installed components to form test point loops. The loops are formed by bending the cutoff leads into a “U” shape and installing them into the test point locations, leaving 6mm or so of loop area above the PC Board. Each test point installs into a pair of pads that are tied together. ( ) TP1 U-shaped lead ( ) TP2 U-shaped lead ( ) TP3 U-shaped lead ( ) TP4 U-shaped lead ( ) TP5 U-shaped lead ( ) TP6 U-shaped lead ( ) TP7 U-shaped lead

Step 6

Install the slide switch: It is not necessary to trim the leads of this component after installation. ( ) SW1 Slide switch

Step 7 Install the 3.5mm jacks. One jack will be used for the key, the other will be used for the headphones. The two jacks supplied in the kit are identical and may be installed in either location. It is not necessary to trim the leads of this component after installation. ( ) J2 Key jack ( ) J3 Headphone jack


Step 8 Install the 8 pin DIP socket. This component must be installed in a specific orientation. Note that the component outline for U1 on the PC board is a rectangle with a semi-circular cutout at one end. The 8 pin DIP socket has a semi-circular notch at one end. Align the notch on the socket with the cutout on the component outline when inserting the socket into the PC board. It is not necessary to trim the leads of this component after installation. ( ) U1 8 pin DIP socket

Step 9 Install the transistors: These components must be installed in a specific orientation. Note that the component outline for Q1 and Q2 are a semi-circle with one flat side. The flat side on the transistor must align with the flat side on the component outline on the PC board. The leads of the transistors will need to be spread slightly to match the pad layout on the PC board. When installing Q1 and Q2, insert them until you feel resistance and then stop.

DO NOT try to force Q1 and Q2 all the way down to the surface of the PC board. ( ) Q1 2N3904 TO92 case ( ) Q2 2N3904 TO92 case


Step 10

Install the trimmer potentiometer: It is not necessary to trim the leads of this component after installation. ( ) R2 10k trimmer potentiometer

Step 11

Install the LED: This component must be installed in a specific orientation. Note that the component outline for D2 has a vertical line next to the square pad. This vertical line, and the square pad, indicate the cathode side of the LED. The cathode lead on the LED is the SHORT lead. Make sure the SHORT lead of the LED is installed in the SQUARE pad with the longer lead being installed through the round pad. Due to the shape of the leads on the LED it will not be possible to seat it flush to the surface of the PC Board. It is normal for the base of the LED to be slightly above the surface of the PC Board. ( ) D2 Green LED

Step 12

Install the electrolytic capacitors: These components must be installed in a specific orientation. Note that the component outline for C5 and C8 each have a “+” (plus) sign next to the square pad. Electrolytic capacitors are marked to indicate the negative lead of the capacitor. Once you identify the negative lead, the other lead is the positive lead. The POSITIVE lead is installed in the SQUARE pad with the “+” sign next to it. The NEGATIVE lead is installed in the ROUND pad. IMPORTANT: If an electrolytic capacitor is installed backwards, it can be destroyed when power is applied.


( ) C5 10uF Electrolytic Capacitor ( ) C6 10uF Electrolytic Capacitor ( ) C8 100uF Electrolytic Capacitor Note: Refer to Figure 2 on page 5 for a diagram of a typical electrolytic capacitor installation.

Step 13

Install the volume control potentiometer: It is not necessary to trim the leads of this component. ( ) R12 10k potentiometer

Step 14

Install the 9 Volt battery snap connector: The wires for the Battery Snap connector attach to the pads marked J1 on the PC board. The RED wire must be soldered to the square pad marked “+” and “RED”. The BLACK wire solders to the round pad marked “COM” and “BLACK”. ( ) J1 9 Volt Battery Snap connector


Step 15

Install the NJM386 audio amplifier IC (U1) into the 8 pin DIP socket previously installed. This device must be installed in a specific orientation. The NJM386 IC has a semi-circular notch on one end and/or a small dimple indicating pin 1. The IC must be positioned such that the notch or dimple are toward the notch on the previously installed DIP socket at U1. The pins on ICs are supplied slightly spread and must be straightened prior to installation. The pins are easily straightened by laying the IC on its side, on a flat surface, and gently rotating it to straighten the pins. Refer to the illustration below. ( ) U1 NJM386 Audio Amplifier (assure that the IC is pushed all the way into the socket)


Step 17

Install the Battery Holder: Refer to the figure below. ( ) BT1 Battery Holder ( ) M2 x 4mm Screw (quantity 2) ( ) M2 Hex Nut (quantity 2)

Battery Holder Installation


Step 18 Install the nylon screw supports: Refer to figure below. ( ) M3 x 10mm Nylon Screw (quantity 4) ( ) M3 Nylon Hex Nut (quantity 4)

KIT ASSEMBLY IS COMPLETE

Nylon Screw Support Installation (9V Battery Snap Connector Not Shown for Clarity)


Operation Initial Control Settings ( ) Make sure the main power switch, SW1, is in its leftmost (Off) position. ( ) Set the TONE ADJ trimmer, R2, to its mid-point position. ( ) Turn the VOLUME control, R12, all the way counter-clockwise (all the way to the left). Connections ( ) Connect a fresh 9V battery to the battery snap connector and insert the battery into the battery

holder. ( ) Plug a straight key into the KEY jack, J2. Note: If a straight key is not immediately available, the CPO1 can be tested by tacking a length

of wire to TP3 and touching the other end of the wire to TP1 or TP7 (both are connected to COM).

( ) Plug stereo headphones into the PHONES jack, J3. Note: Do not wear the headphones until after power is applied. There can be a loud pop in the headphones when power is applied. ( ) Turn on power by sliding the power switch, SW1, to its rightmost position. ( ) Confirm that the GREEN LED, D2, is illuminated. The GREEN LED is provided as a power on

indicator. ( ) While wearing the headphones, depress the straight key and adjust the VOLUME control, R12,

for the desired volume. ( ) Adjust the trimmer R2, TONE ADJ, for the desired tone. The CPO1 Code Practice Oscillator is now ready for use. To prolong battery life, turn the CPO1 off when it is not actively in use. If the CPO1 is not going to be used for more than one week, remove the battery.


Troubleshooting If the CPO1 is not working properly, the following information may help. It is worth noting that it is rare to discover a faulty component. Most problems can be traced to a poor or missing solder connection or a component that is installed improperly or in the wrong place. There are 7 test points on the PC board that provide a convenient connection for probing signal levels at various points in the circuit. The test points are connected as follows: TP1 COM (common) on the left side of the PC board TP2 Output of the Twin-T oscillator circuit, before the coupling capacitor C4 TP3 The keying circuit TP4 +V TP5 Output of the buffer amplifier after the coupling capacitor C6 TP6 Output of U1, the NJM386 audio amplifier TP7 COM (common) on the right side of the PC board If you are still having problems after trying the tips in the chart below, re-check all of your solder connections, double check the polarity of C5, C8, D1, Q1, and Q2. Confirm that U1 is oriented properly and that all the pins are inserted into the socket.

Problem Things to Try

The GREEN LED, D2, does not illuminate when the power switch is in the ON position.

1. Be sure there is a fresh battery installed. 2. Check that the battery connector leads are properly soldered to

the correct pads. 3. Check that the 1N4007 diode, D1, is installed in the proper

orientation. 4. With the power switch, SW1, in the ON position, check the

voltage at TP4. It should be around 8.5VDC with a fresh battery installed. If the voltage reading checks out and the LED is still not illuminated, it is likely that the LED was installed backwards.

There is no tone when the key is closed.

1. Check that a fresh battery is installed, that the power switch, SW1, is in the ON position and that the VOLUME control, R12, is not all the way counter-clockwise.

2. Check that the headphones you are using are working. Try them in another device that is known to work properly.

3. Check the wiring of the plug connected to the straight key. There should be two wires between the plug and the straight key. One wire should connect to either the TIP or RING of the 3.5mm plug and the other wire should connect to the plug’s sleeve.

4. Check the installation of U1 in the 8-pin DIP socket. It is possible that one or more pins were bent under the body of the IC when the IC was installed in the socket.

5. One or more of the parts in the twin-t oscillator circuit around Q1 may have been installed in the wrong location(s). Recheck the markings on R1, R3, R4, R5, R7 and C1, C2, C3.

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