Aj SigGen PS Tech Manual Final

Aj-SigGen-PS Version 1.0

www.ajoyraman.in

Aj-Signal-Generator-and-Power-Supply

Technical Manual

Aj – SigGen – PS Technical Manual

www.ajoyraman.in Page 1 of 9

1. Introduction:

This is a brief manual containing relevant technical data required for understanding, construction and use of the Aj-SigGen-PS unit.

This unit is designed to compliment the Aj-Simple-Scope and serve as a teaching aid for budding engineers, electronic enthusiasts and hobbyists.

This USB connected unit implements a microcontroller based DDS Signal Generator providing Sin and Triangular waveforms with adjustable magnitude and offset up to 50 kHz. TTL and 1 V square waves are simultaneously provided. Additionally ± 12V and a variable +2 to 7V output with a total capacity of 1W are provided to power external circuits under test.

2. Warning & Disclaimer:

All content provided in this document is for informational purposes only. The owner of this document makes no representations as to the accuracy or completeness of any information. The owner will not be liable for any errors or omissions in this information. The owner will not be liable for any losses, injuries, or damages from the display or use of this information including software.

3. Block Schematic and Function Description

+2 T

O 7

V

RET

+12V

-12V

RET RET

+2 T

O 7

V

TTL

RET

1V SQ

POT 1 3

2

USB +5V

D-D+

5V RET

PIC18F14K50 PIC18F14K50

DC-DC CONVERTER

USB-INTERFACE DDS GENERATORDAC1OFFSET

DA

C2

AM

PLITUD

ELINEARREGULATOR

Aj - SigGen - PS

Figure 1, Aj-SigGen – PS simplified block schematic

Figure 1 shows the simplified block schematic of the system. For ease of portability the unit is powered and controlled from the USB port of a PC.



Two PIC18F14K50 microcontrollers are used to provide the functionality of the unit.

The first PIC microcontroller implements the following functions:

Communicates with the host PC for enumeration as a USB to UART device

Sets up the unit as a 500mA device

Switches on power to the DC-DC converter

Provides the complimentary square wave drive to the DC-DC converter

Acts as a USB communication interface to the second PIC

Provides the Amplitude reference for DAC2

Provides the digital word for DAC1 giving the offset value.

The second PIC microcontroller implements the remaining DDS functions

Direct Digital Synthesis (DDS) signal generation

Sin/ triangle word output to DAC2

TTL and 1 V square reference output

The DC-DC converter is a driven 1W, 5V to ± 12V operating at 100 kHz. The +12 V output is fed to a linear regulator to provide a variable +2 to 7 V output controlled by a variable potentiometer.

The DC-DC converter provides full protection to the host PC USB port as its outputs are short circuit and current limit protected.

The circuit under test can be rigged up on a standard breadboard and powered from the power sockets provided.

4. Software on the PC Host:

A Visual Basic .Net 2.0 based GUI program is used to control the functions of the Aj-SigGen – PS unit. An Aj_SigGen.exe along with associated USB driver files has been tested for compatibility with Windows XP and Windows 7 with .net 2.0.



5. GUI:

Figure 2, GUI

The GUI based Windows software on the Host PC permits checking for available COM ports and connecting to the port on which the hardware is connected.

Once connected the hardware unit responds with a ready signal.

Waveform type, frequency, amplitude and offset can be set using the simple controls.

The RUN button initiates the signal output and indicates the waveform set.

An EXIT button is provided to close the program and exit.



6. Aj-SigGen-PS Unit, Front and Rear Panels:

Figure 4, Showing Aj-SigGen-PS Unit

Figure 4, Front panel showing connectors, LED’s and Potentiometer

Figure 5, Rear panel showing USB connector and Reset switch



7. Circuit Diagrams:

Figure 6, USB interface and DDS signal generation



Figure 7, USB powered DC-DC converter



8. Bill of materials



9. Printed Circuit Boards :

Figure 8, Component Layout

Figure 9, Wired PCB top view



10. Appendices

DDS Signal Generator Circuit

DC-DC Converter Circuit

Component layout

PCB 1:1 A4 Top mirrored

PCB 1:1 A4 Bottom

11. Summary

This document provides essential information for fabrication and operation of the Aj-SigGen-PS unit.

Software can be downloaded from my website http://www.ajoyraman.in

Address any doubts and clarifications to me at [email protected]

5

5

4

4

3

3

2

2

1

1

D D

C C

B B

A A

WAVEFORM CENTERING

OFFSET +2.5V TO-2.5V 64 STEPS

AMPLITUDE0-5V 32STEPS

OFFSETCENTERING

DAC GAIN x 2OUTPUT 16V P MAX 32STEPS (0.32V) OFFSET +4V TO -4V 64STEPS (0.16V)

COMPLIMENTARYPWM DRIVE50kHZ

RESET FROMPIC1

SQUARE WAVEREFERENCE

Aj_SigGen_PS_Feb 13 NIL

DDS SIG GEN WITH DUAL 12V AND VARIABLE 2-7V POWER SUPPLY

A

1 2Tuesday, February 05, 2013

Title

Size Document Number Rev

Date: Sheet of

+5VG N D

50 K

HZ

0P

H

50 K

HZ

180

PH

- 12VOUT

VVAROUT

+12V0UT

P S O N

FILT

FILT

+5V

+5V

-12V

+12V

+12V

-12V

-12V

-12V

+12V

+12V

+12V

-12V

+12V

-12V

-12V

+5V

+5V+5V

U4P

IC18

F14

K50

16 155 6 7 8 9 10

111213

120 14

431719 18

2

RC

0R

C1

RC

5/P

IAR

C4/

PIB

RC

3R

C6

RC

7R

B7/

TX

RB

6R

B5/

RX

RB

4

VD

DV

SS

RC

2/C

VR

EF

MC

LR/V

PP

OS

C2/

CLO

VU

SB

PG

D/D

+P

GC

/D-

OS

C1/

CLI

U2

PIC

18F

14K

50

16 155 6 7 8 9 10

111213

120 14

431719 18

2

RC

0R

C1

RC

5/P

IAR

C4/

PIB

RC

3R

C6

RC

7R

B7/

TX

RB

6R

B5/

RX

RB

4

VD

DV

SS

RC

2/C

VR

EF

MC

LR/V

PP

OS

C2/

CLO

VU

SB

PG

D/D

+P

GC

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OS

C1/

CLI

U3

DAC0800

2

53

76

4

8

1

9 10 11 12

16

14

15

13

-

D7

V-

D5

D6 +D4

VLC

D3

D2

D1

D0

C

R+

R- V+

U5

DAC0800

2

53

76

4

8

1

9 10 11 12

16

14

15

13

-

D7

V-

D5

D6 +D4

VLC

D3

D2

D1

D0

C

R+

R- V+

J3 USB

1234

C2470p

R220K

U1ALF353

3

2

84

1+

-

V+

V- O U T

U1BLF353

5

6

84

7

+

-

V+

V-

O U T

R85K

R510K

R310K

R4 10K

J1

12V OUT

1 2 3

J4

S IGOUT

12345678

J2

VVAR OUT

1 2

C1 33PF

C3

100PF

R105K

C40.01u

C100.01u

C1110u

C810u

C5

0.1u

C120.1u

Y2 12MHz

Y112MHz

C1322p

C1422p

C622p

C722p

R6 3.9K

R71K

J5 RESET

1 2

R9R

C90.1u

R1 16.8K

5

5

4

4

3

3

2

2

1

1

D D

C C

B B

A A

10TBIF#28

DU

AL

12V

OU

TP

UT

30TBIF#34

C U R R E N TLIMIT SET

MAHINDRA HINODAYTORROID 12X4M S B 5S

C U R R E N TSENSE

FR

OM

PIC

1F

RO

M

PC

US

B P

OR

T

DR IVEN PUSH-PULLC O N V E R T E R

Aj_SigGen_PS_Feb 13 NIL

DDS SIG GEN WITH DUAL 12V AND VARIABLE 2-7V POWER SUPPLY

A

2 2Tuesday, February 05, 2013

Title

Size Document Number Rev

Date: Sheet of

50 KHZ 0PH

50 KHZ 180PH

+5V

-12VOUT

+12V0UT

P S O N

VVAROUT

G N D

+ 12V

- 12V

- 12V

USB +5V

USB +5V

USB +5V

+ 12V

C1847UF 25V

ISO2PC817

D6LED RED R15 2.7K

R141K

Q4RFP12N10L

Q1IRF9540

D1 1N5819

Q3RFP12N10L

T1

Q2BC107

R220.25

C17330UF 25V

R19

22K

C201UF 100V

R12 100

D4 1N5819

D5 1N5819

D2 1N5819

+

-

U7LM741

3

26

74 C21

47UF 25V

R20 5.6K

C1647UF 25V

C1547UF 25V

U6LM117

2 3

1

IN O U T

AD

J

R214.7K

R1733K

R16

1K

R231K

C19

1UF 16V

R24390

D7 1N914

D8 1N914

R13220K

R18100K

ISO1PC817

D3LED GREEN

R1122K

Aj SigGen PS Tech Manual Final

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