platino signal generator (130407-1)

Bare PCB # 130407-1 for the project Experimenter's Function Generator, as published in Elektor Magazine edition January/February 2015.

This simple Platino-based Signal Generator is designed for not too demanding (hobbyist) applications. It is usable for applications like signal tracing, clocking of MCU circuits, audio filter & loudspeaker testing, tuning, etc.

A Signal generator device generates signals of different frequencies. The Platino Signal generator device uses the Elektor’s Platino board to design a real time, straight forward, non complicated design of the Signal generator. Inspired by Elektor’s AVR SDR project.

Specifications:

• DC Input: 18 V to 20 VDC
• Elektor Platino with ATMEGA1284P microcontroller
• 20 X 4 LCD Display
• Standard BNC type connectors for outputs / input
• One square wave output up to 10 MHz, 5 V and 3.3 V output level switchable
• Other outputs: Sine, Square, triangular, Sawtooth, Inv Sawtooth, Pulses, Arbitrary and Random (Noise)   
• One Frequency Modulation input

Features:

1. Programmable waveform output of different types of waves up to 100 KHz is given as output by the device through connector K6
2. Square wave output, 5 V and 3.3 V selectable DC voltage output signal through connector K5
3. Frequency Modulation input through connector K7
4. All selections are set using a single rotary encoder with push button and a back button
5. The device can be powered from a standard 18 V laptop power adapter
6. Setup mode for Arbitrary and Clock mode
7. Normal mode for other output waveforms

Amplitude, frequency, Offset of waveform can be changed in real time. 

Component list

On Signal Generator Board:
Resistors
(Default: 5%, 0.25W)
R1,R3,R5,R7,R9,R11,R13,R17 = 10kΩ
R2,R4,R6,R8,R10,R12,R14,R15,R16,R18,R19 = 20kΩ
R20 = 100Ω
R21,R24 = 1kΩ
R22 = 1.8kΩ
R23 = 120Ω
R25,R26 = 8.2kΩ 3.9kΩ
R27,R28 = 1Ω 2W
R29,R30 = 10Ω 68Ω 1%
P1 = 100kΩ multiturn trimpot, vertical

Capacitors
C1 = 100pF
C2,C4 = 470µF 16V radial
C3,C5,C6,C9 = 100nF radial
C7,C8 = 22µF 25V radial
C10,C11 = 1000µF 63V 35V radial
C12 = 470µF 35V radial

Semiconductors
IC1 = TL082ACP
IC2 = (CD)74HC4051
IC3 = LM337KCSE3
IC4 = MC7805
IC5 = LM317TG
IC6 = LM336BZ-2.5V
D1 = BY500-800-E3/4
D2 = BZX79-C5V1
D3,D4 = 1N4007

Miscellaneous
K1 = 10-way pinheader socket strip, SIL, straight
K2 = 8-way pinheader socket strip, SIL, straight
K3 = 12-way pinheader socket strip, SIL, straight
K4 = 6-way (2x3) pinheader socket, double row
K5,K6,K7 = 2-way pinheader, vertical, 0.1” pitch
K8 = 2-way PCB screw terminal block, 0.2” pitch
IC socket, DIP-16
IC socket, DIP-8
PCB no. 130407-1

On Platino*:

Resistors (Default: 5% 0.25W)

R3 = 47Ω
R4,R5,R6,R7,R10,R12 = 10kΩ
R11 = 4.7kΩ
P1 = 10kΩ, trimpot, horizontal

Capacitors
C1,C2 = 22pF, 50V, C0G/NP0, 0.1” pitch
C5,C6 = 100nF, 50V, X7R, 0.2” pitch

Semiconductors
IC1 = ATMEGA1284P-PU, programmed
T1 = BC547C

Inductors
L1 = 10µH

Miscellaneous
IC socket, DIP-40
LCD1 = LCD, 4x20, 5V, with backlight
S5A = rotary encoder with pushbutton
X1 = 20MHz quartz crystal, CL= 18pF
K1,K2,K5 = 40-pin SIL pinheader, vertical
K4 K3 = 6 pins cut from 80-pin double-row pinheader, vertical
K9 = 16 pins cut from 36-way pinheader receptacle (socket), SIL, vertical
S4A = pushbutton

*Please refer to www.elektor-magazine.com/100892 for a full description of Platino (log in required).

More information on the Experimenter's Function Generator project, see:

Platino 1.4 (150555) is compatible with the previous version but there are two new solder jumpers that are, of course, not mentioned in the function generator article: JP15 & JP16. These jumpers control part of the LCD and must be set to ‘D’ for this project (and _ALL_ other “old” Platino projects with an LCD).