Teardown Tuesday: General Bluetooth Multimeter

'General Tools' distributes a variety of measurement tools through home improvement stores and online resellers. Their latest 'Toolsmart' line of tools includes Bluetooth functionality. This week, AAC purchased an auto-ranging Bluetooth multimeter to take apart and peek inside.

About the Multimeter

The Toolsmart line of products by General Tools provides Bluetooth connectivity to several different measurement products that can connect to iPhone and Android smartphones through the manufacturer's provided apps (via the Google Play and iTunes Store). The multimeter used in this teardown is of comparable quality to others in this price class (<$40) with the exception that this one has Bluetooth connectivity. Once connected, data is streamed from the multimeter to an app on the user's phone that can then record and save the data in lists or on top of photographs taken by the smartphone.
Limited testing of the device prior to the teardown showed an easy-to-use app that connected immediately to the multimeter with an iPhone.


The multimeter (intact). Image courtesy of Amazon.

Taking Apart the Multimeter

Disassembly of the multimeter is relatively straightforward. Disconnect and set aside all probes before you begin.
To start, remove the battery case screw and the battery cover. Then remove the soft plastic shell that surrounds and protects the hard plastic case from small bumps and scrapes. The bottom side of the multimeter holds four thermoplastic case screws that hold the two sides of the multimeter together.
For most users, disassembly stops here, as it provides access to the fuses. For others, continue the teardown by removing all visible thermoplastic screws holding the circuit board to the front of the case.
Remove the circuit board from the front half of the case by either pushing the banana plugs through from the front or by patiently and gently pulling on the circuit board to free them from the circuit board side.
See the video below for more information.


A Look Inside


Image shows the reverse of the top-side of the case, the front of the multimeter circuit board and the back of the multimeter circuit board.

Top Side MarkingDescriptionCostMore Information
DTM0660LMultimeter ICDatasheet (Chinese) | Datasheet (English)
24C02AEEPROM$0.1Datasheet | Alternate Datasheet Link
BDE-BLEM201PBluetooth UARTDatasheet

The center image highlights the copper rings (4) that create the rotary selection switch. The right image highlights the important ICs on the circuit board (1 through 3).

(1)  DTM0660L (Pink)

DreamTech International, a Hong Kong-based company manufactures the DTM0660 integrated circuit. It is a very popular multimeter microcontroller that performs all of the analog-to-digital (ADC) conversion and drives the LCD display. Configuration data is stored in an external EEPROM.
The datasheet for the DTM0660 is written in Chinese. Fortunately, a bilingual engineer named Kerry Wong translated the datasheet, including the bitmap, into English. If you need to modify a DTM0660-based multimeter, his site appears to be a great place to start as it provides information on reading and writing the I²C based EEPROM.

   
 

(2)  T24CO2A (Yellow)

This is a two-kilobyte I²C EEPROM that stores the configuration information for the main microcontroller. It accompanies the DTM0660 multimeter IC so frequently that its presence allows hobbyists and hackers to surmise the presence of the DTM0660 circuitry beneath the epoxy of inexpensive chip-on-board multimeter designs.


Schematic used courtesy of Atmel via Mouser.

(3)  BDE-BLEM201P (Blue)


Image courtesy of BDE
 
This decidedly small module integrates a Bluetooth Low Energy (BLE) radio, the Bluetooth software stack, and an 8051 microcontroller.  It has 23 General Purpose Input/Output pins, 8K Ram, 128K flash memory, and supports one I²C and two USART interfaces.


Image courtesy of BDE
 
These modules seem to be purpose built for painless pairing with cell phones, and a datasheet for a different product that the company sells also bore pictures that resembled the 'General Tools' app.  Unfortunately, the datasheet was written entirely in Chinese, and the email I sent to the company has not been returned.  My suspicion is that the company facilitates app development by providing code and structure for iPhone and Android apps.

(4) Rotary Selection Switch (Orange)

Specialty switches can be expensive and, in certain instances, electrical engineers can save a great deal of money by designing their own out of copper traces and copper spring contacts.
As I mentioned in the previous teardown of a different device, users need to know that the switch is in position, and solutions can be inexpensively engineered by including cantilevered cams with corresponding indentations. This solution works for linear and rotary switches.
The mechanical engineer of this device used four cams and indentations on the back side of the multimeter knob to simultaneously provide physical feedback for users and to positively lock the dial in position.

 

Conclusion

I would like to again point out that AAC purchased this multimeter for this teardown and that we have no ties to General Tools.
Recently, I have been tearing down quite a few Bluetooth tools, and am usually so disappointed by their lack of functionality that I do not bother to reassemble them. I put this multimeter back together immediately after the teardown.

If you need a Bluetooth-connected multimeter and have a few dollars to spend ($33.50 at Home Depot at the time of publication), this is certainly worth consideration.  
Previous
Next Post »
My photo

Hi, I`m Sostenes, Electrical Technician and PLC`S Programmer.
Everyday I`m exploring the world of Electrical to find better solution for Automation. I believe everyday can become a Electrician with the right learning materials.
My goal with BLOG is to help you learn Electrical.
Related Posts Plugin for WordPress, Blogger...

Label

KITAIFA NEWS KIMATAIFA MICHEZO BURUDANI SIASA TECHNICAL ARTICLES f HAPA KAZI TU. LEKULE TV EDITORIALS ARTICLES DC DIGITAL ROBOTICS SEMICONDUCTORS MAKALA GENERATOR GALLERY AC EXPERIMENTS MANUFACTURING-ENGINEERING MAGAZETI REFERENCE FUNDAMENTAL OF ELECTRICITY ELECTRONICS IOT ELECTRICAL ENGINEER MEASUREMENT VIDEO ZANZIBAR YETU TRANSDUCER & SENSOR MITINDO RENEWABLE ENERGY ARDUINO AUTOMOBILE SYNCHRONOUS GENERATOR ELECTRICAL DISTRIBUTION CABLES DIGITAL ELECTRONICS AUTOMOTIVE PROTECTION SOLAR TEARDOWN DIODE AND CIRCUITS BASIC ELECTRICAL ELECTRONICS MOTOR SWITCHES CIRCUIT BREAKERS CIRCUITS THEORY MICROCONTROLLER PANEL BUILDING ELECTRONICS DEVICES MIRACLES SWITCHGEAR ANALOG MOBILE DEVICES CAMERA TECHNOLOGY GENERATION BATTERIES FREE CIRCUITS INDUSTRIAL AUTOMATION SPECIAL MACHINES WEARABLES COMMUNICATION ELECTRICAL SAFETY ENERGY EFFIDIENCY-BUILDING DRONE NUCLEAR ENERGY CONTROL SYSTEM FILTER`S SMATRPHONE BIOGAS POWER TANZIA BELT CONVEYOR MATERIAL HANDLING RELAY ELECTRICAL INSTRUMENTS PLC`S TRANSFORMER AC CIRCUITS CIRCUIT SCHEMATIC SYMBOLS DDISCRETE SEMICONDUCTOR CIRCUITS WIND POWER C.B DEVICES DC CIRCUITS DIODES AND RECTIFIERS FUSE SPECIAL TRANSFORMER THERMAL POWER PLANT cartoon CELL CHEMISTRY EARTHING SYSTEM ELECTRIC LAMP FUNDAMENTAL OF ELECTRICITY 2 BIPOLAR JUNCTION TRANSISTOR ENERGY SOURCE 555 TIMER CIRCUITS AUTOCAD C PROGRAMMING HYDRO POWER LOGIC GATES OPERATIONAL AMPLIFIER`S SOLID-STATE DEVICE THEORRY DEFECE & MILITARY FLUORESCENT LAMP HOME AUTOMATION INDUSTRIAL ROBOTICS ANDROID COMPUTER ELECTRICAL DRIVES GROUNDING SYSTEM BLUETOOTH CALCULUS REFERENCE DC METERING CIRCUITS DC NETWORK ANALYSIS ELECTRICAL SAFETY TIPS ELECTRICIAN SCHOOL ELECTRON TUBES FUNDAMENTAL OF ELECTRICITY 1 INDUCTION MACHINES INSULATIONS ALGEBRA REFERENCE HMI[Human Interface Machines] INDUCTION MOTOR KARNAUGH MAPPING USEUL EQUIATIONS AND CONVERSION FACTOR ANALOG INTEGRATED CIRCUITS BASIC CONCEPTS AND TEST EQUIPMENTS DIGITAL COMMUNICATION DIGITAL-ANALOG CONVERSION ELECTRICAL SOFTWARE GAS TURBINE ILLUMINATION OHM`S LAW POWER ELECTRONICS THYRISTOR USB AUDIO BOOLEAN ALGEBRA DIGITAL INTEGRATED CIRCUITS FUNDAMENTAL OF ELECTRICITY 3 PHYSICS OF CONDUCTORS AND INSULATORS SPECIAL MOTOR STEAM POWER PLANTS TESTING TRANSMISION LINE C-BISCUIT CAPACITORS COMBINATION LOGIC FUNCTION COMPLEX NUMBERS ELECTRICAL LAWS HMI[HUMANI INTERFACE MACHINES INVERTER LADDER DIAGRAM MULTIVIBRATORS RC AND L/R TIME CONSTANTS SCADA SERIES AND PARALLEL CIRCUITS USING THE SPICE CIRCUIT SIMULATION PROGRAM AMPLIFIERS AND ACTIVE DEVICES BASIC CONCEPTS OF ELECTRICITY CONDUCTOR AND INSULATORS TABLES CONDUITS FITTING AND SUPPORTS CONTROL MOTION ELECTRICAL INSTRUMENTATION SIGNALS ELECTRICAL TOOLS INDUCTORS LiDAR MAGNETISM AND ELECTROMAGNETISM PLYPHASE AC CIRCUITS RECLOSER SAFE LIVING WITH GAS AND LPG SAFETY CLOTHING STEPPER MOTOR SYNCHRONOUS MOTOR AC METRING CIRCUITS BASIC AC THEORY BECOME AN ELECTRICIAN BINARY ARITHMETIC BUSHING DIGITAL STORAGE MEMROY ELECTRICIAN JOBS HEAT ENGINES HOME THEATER INPECTIONS LIGHT SABER MOSFET NUMERATION SYSTEM POWER FACTORS REACTANCE AND IMPEDANCE INDUCTIVE RESONANCE SCIENTIFIC NOTATION AND METRIC PREFIXES SULFURIC ACID TROUBLESHOOTING TROUBLESHOOTING-THEORY & PRACTICE 12C BUS APPLE APPS & SOFTWARE BATTERIES AND POWER SYSTEMS ELECTROMECHANICAL RELAYS ENERGY EFFICIENCY-LIGHT INDUSTRIAL SAFETY EQUIPMENTS MEGGER MXED-FREQUENCY AC SIGNALS PRINCIPLE OF DIGITAL COMPUTING QUESTIONS REACTANCE AND IMPEDANCE-CAPATIVE RECTIFIER AND CONVERTERS SEQUENTIAL CIRCUITS SERRIES-PARALLEL COMBINATION CIRCUITS SHIFT REGISTERS BUILDING SERVICES COMPRESSOR CRANES DC MOTOR DRIVES DIVIDER CIRCUIT AND KIRCHHOFF`S LAW ELECTRICAL DISTRIBUTION EQUIPMENTS 1 ELECTRICAL DISTRIBUTION EQUIPMENTS B ELECTRICAL TOOL KIT ELECTRICIAN JOB DESCRIPTION LAPTOP THERMOCOUPLE TRIGONOMENTRY REFERENCE UART WIRELESS BIOMASS CONTACTOR ELECTRIC ILLUMINATION ELECTRICAL SAFETY TRAINING FILTER DESIGN HARDWARE INDUSTRIAL DRIVES JUNCTION FIELD-EFFECT TRANSISTORS NUCLEAR POWER VALVE WWE oscilloscope 3D TECHNOLOGIES COLOR CODES ELECTRIC TRACTION FLEXIBLE ELECTRONICS FLUKE GEARMOTORS INTRODUCTION LASSER MATERIAL PID PUMP SCIENCE SEAL ELECTRICIAN CAREER ELECTRICITY SUPPLY AND DISTRIBUTION FEATURED MUSIC NEUTRAL PERIODIC TABLES OF THE ELEMENTS POLYPHASE AC CIRCUITS PROJECTS REATORS SATELLITE STAR DELTA VIBRATION WATERPROOF