Elektor Quasi Analog Clockwork Kit Construction Manual

V1.0 - June 11, 2024

© Elektor International Media b.v.

This manual is available as a downloadable PDF. You can find this essential document at the following address: www.elektor.com/20944

Table of Contents

• 1 - Kit Contents
• 2 - Tools Needed
• 3 – Assembling the PCB
• 4 – Adjusting trimmer capacitor C7
• 5 - Bill of Materials
• 6 - Specifications
• 7 - Web Links
• 8 - Schematic and PCB Layout

1 - Kit Contents

The kit supplied by Elektor contains the PCB and all parts stated in the Bill of Materials found in section 5.

The following description details the components included in the kit, as shown in a typical kit photo:

Figure 1: Components contained in the Elektor Quasi-Analog Clockwork kit. This image displays a variety of electronic components neatly organized, including integrated circuits (ICs), resistors, capacitors, LEDs (both red and green), transistors, a crystal oscillator, a tactile switch, and a terminal block. These components are typically supplied in bags or strips, ready for assembly onto the printed circuit board.

The following images show the top and bottom side of the PCB contained in the kit.

Figure 2: Top view of supplied PCB 240118-1 v1.1. This image shows the component side of the printed circuit board (PCB) for the Quasi-Analog Clockwork. It features a circular arrangement of pads for LEDs, with numerical markings from 1 to 12 around the perimeter, resembling a clock face. Various component footprints for ICs, resistors, capacitors, and transistors are visible across the board, along with silkscreen labels indicating component designators and the 'Elektor CLASSIC' logo. The board is black with white silkscreen.

Figure 3: Bottom view of supplied PCB 240118-1 v1.1. This image displays the solder side of the printed circuit board (PCB). It shows the copper traces and solder pads for all components. The circular LED arrangement is clearly visible from this side, along with the pads for ICs and other through-hole components. The 'Elektor CLASSIC' logo and board identification 'ELEKTOR 240118-1' are also present.

2 - Tools Needed

• Soldering equipment for through-hole components, including a soldering iron with a relatively small tip.
• Cutting pliers.
• Flat-jaw pliers.
• A flat and clean surface to place the PCB on when soldering the components.

3 - Assembling the PCB

Start by placing the lowest components first and solder them. The quartz crystal, X1, is the smallest and most fragile component and is best fitted when the rest of the components are placed and soldered. In the case of diodes, pay attention to the cathode marking. First solder one lead and check polarity again – it's easier to remove a diode with just one lead soldered. When turning over the PCB to solder the leads, make sure the surface is perfectly flat. After soldering the first leads – also applicable to the resistors – check if the body of every component is level and flush on the PCB surface. Then solder the second lead of each component.

Place the following components and solder them in this order:

1. Diodes D145 – D156
2. Resistors R1 – R26
3. Diode D164
4. Tactile switch S1
5. All IC sockets: first solder 2 pins in opposite corners of each IC socket and check they are all fitted correctly; then solder the rest.
6. Capacitors C5 (22 pF) and C6 (10 pF)
7. Capacitors C1 – C4, C8 – C18
8. LEDs D1 – D144, D162, D163

The short leads (i.e., cathodes) of the LEDs in the circle are on the outside. When soldering, pay close attention to this! Place one LED at a time and solder one lead of each LED only and check if it's placed perpendicular with the PCB surface and if the last LED soldered lines up perfectly with the previously soldered ones. Check if this is the case, with every LED, every time! Also place the green LEDs in the correct position. Between two green LEDs go 11 red LEDs. If everything looks good it's safe to solder the second lead of each LED. Before soldering, make 12 stacks of 12 LEDs, 11 red and 1 green. This is to remind you that after 11 red LEDs one green LED must be soldered. Placing all 144 LEDs in the circle first and soldering them all at once will not work since the transparent plastic of the LEDs is subject to tolerances too much, and the holes in the pads are larger than the LED wire diameter.

Proceed with soldering:

9. Trimmer C7
10. Transistors T1 and T2
11. Terminal block K1 (place it on the bottom side, see Figure 5 description)
12. Crystal X1

4 – Adjusting Trimmer Capacitor C7

Adjusting C7 requires a frequency counter with at least 7 digits. Many modern multimeters with a graphical display are also able to measure frequency but not that accurately. The latter can be used to get an indication whether or not the 8 Hz deviates too much. Measure at pin 1 of IC1. If an accurate frequency measurement isn't possible, adjust the trimmer halfway. A quote from the datasheet published for the trimmer used (BFC280823109): “Life of trimmer is specified as 10 cycles maximum, rotation in 180° only (is the effective angle of rotation). The electrical and mechanical performance is not guaranteed if rotated beyond 10 cycles.” Also solder the trimmer as close as possible to the board!

Figure 6: PCB powered and secured in wooden stand. This image shows the assembled Elektor Quasi Analog Clockwork Kit mounted vertically in a light-colored wooden stand. The black PCB with its circular arrangement of red and green LEDs is clearly visible, powered on, with some LEDs illuminated to indicate a time between 5 and 10 minutes past 1 o'clock. The Elektor LABS logo is visible on the wooden stand.

Figure 7: Another view of the clock in the wooden stand. This image provides another perspective of the assembled clock kit in its wooden stand. The LEDs are illuminated to show a time between 10 and 15 minutes past 1 o'clock. The overall setup demonstrates the functional appearance of the finished product.

Figure 8: Side view on the clock in the wooden stand. This image shows a side profile of the assembled clock kit in its wooden stand, highlighting the slim profile of the PCB and how it is secured. The illuminated LEDs are visible from this angle, indicating a time between 10 and 15 minutes past 1 o'clock, similar to Figure 7.

5 - Bill of Materials

Resistors

(body 2.5 x 6.8mm, 250mW)

• R1, R22, R24 = 2.2kΩ
• R2 = 390kΩ
• R3, R5, R6, R7 = 82kΩ
• R4 = 1kΩ
• R8, R9, R10, R11, R12, R13, R14, R15, R16, R17, R18, R19 = 8.2kΩ
• R20 = 20MΩ
• R21 = 330kΩ
• R23 = 560Ω
• R25 = 470Ω
• R26 = 100kΩ

Capacitors

• C1, C2, C3, C4, C8, C9, C10, C11, C12, C13, C14, C15, C16, C17, C18 = 100nF, 50V, ceramic X7R, lead spacing 5mm
• C5 = 22pF, 50V, 5 %, ceramic C0G/NP0, lead spacing 5mm
• C6 = 10pF, 50V, 5 %, ceramic C0G/NP0, lead spacing 5mm
• C7 = 3~10 pF, trimmer capacitor, 150V, through hole (BFC280823109 Vishay BCcomponents)

Semiconductors

• D1, D13, D25, D37, D49, D61, D73, D85, D97, D109, D121, D133 = LED green, 3mm (T1), flat side, no ledge
• D2-D12, D14-D24, D26-D36, D50-D60, D62-D72, D74-D84, D86-D96, D98-D108, D110-D120, D122-D132, D134-D144, D162, D163 = LED red, 3 mm (T1), flat side, no ledge
• D145, D146, D147, D148, D149, D150, D151, D152, D153, D154, D155, D156 = 1N4148, DO-35
• D164 = 1N4004, DO-41
• T1, T2 = BC547B, TO-92
• IC1 = CD4060, DIP-16
• IC2 = 74HC21, DIP-14
• IC3, IC4 = 74HC132, DIP-14
• IC5, IC6 = 74HC4024, DIP-14
• IC7, IC8, IC9, IC10 = 74HC4051, DIP-16
• IC11 = 74HC4040, DIP-16

Miscellaneous

• K1 = 2-way wire-to-board terminal block, 3.5mm pitch
• S1 = 6mm tactile push button
• X1 = 32.768kHz crystal, 20ppm, Cload 12.5pF, 8x3mm cylinder package
• IC2, IC3, IC4, IC5, IC6 = IC socket, DIP, 14 contacts
• IC1, IC7, IC8, IC9, IC10, IC11 = IC socket, DIP, 16 contacts
• PCB no. 240118-1 v1.1

6 - Specifications

7 - Web Link

Project as published on Elektor Labs: https://www.elektormagazine.com/labs/quasi-analog-clockwork-an-elektor-classic-a-remake

8 - Schematic and PCB Layout

This section provides detailed descriptions of the circuit schematic and various PCB layouts, which are essential for understanding and assembling the Elektor Quasi Analog Clockwork Kit.

Figure 9: Schematic of the Quasi-Analog Clockwork (240118-1 v1.1). This diagram illustrates the complete electronic circuit of the clock. It shows the interconnections of all components, including the CD4060 oscillator (IC1) with its 32.768 kHz crystal, the 74HC4040 counter/divider (IC11), 74HC4024 counters (IC5, IC6), 74HC4051 multiplexers/demultiplexers (IC7, IC8, IC9, IC10), and logic gates (74HC21, 74HC132). The schematic details the power supply connections, the LED matrix driving circuitry, and the clock setting mechanism via pushbutton S1. Resistor and capacitor values, as well as diode types, are clearly indicated.

Figure 10: Top overlay of PCB 240118-1 v1.1 of the Quasi-Analog Clockwork. This image displays the silkscreen layer of the top side of the PCB, showing component outlines, designators (e.g., R1, C1, IC1), and polarity markings for diodes and electrolytic capacitors. The circular arrangement for the 144 LEDs is prominent, with numerical hour indicators. This overlay is crucial for correct component placement during assembly.

Figure 11: Bottom overlay of PCB 240118-1 v1.1 of the Quasi-Analog Clockwork. This image presents the silkscreen layer of the bottom side of the PCB. It shows similar component outlines and designators as the top overlay, but from the reverse perspective. This view is helpful for understanding component placement from the solder side, especially for through-hole components.

Figure 12: Copper top of PCB 240118-1 v1.1 of the Quasi-Analog Clockwork. This image shows the copper traces on the top layer of the PCB. It highlights the intricate routing of signals and power lines connecting the various components, particularly the radial traces leading to the LED pads arranged in a circle. Vias (small holes connecting layers) are also visible.

Figure 13: Copper bottom of PCB 240118-1 v1.1 of the Quasi-Analog Clockwork. This image displays the copper traces on the bottom layer of the PCB. It reveals the ground plane and signal routing on this side, complementing the top layer. The circular pattern of traces for the LEDs is also evident from this perspective, demonstrating the compact and efficient design.