The RadioShack 24-Range LCD Digital Multimeter (Cat. No. 22-805)
is a portable, compact device designed for home, shop, and field applications. It features a
-digit display (up to 3,999 units) and unique PC connectivity via an RS-232 interface. Key Features
Measurement Ranges: Includes 24 ranges for DC/AC voltage, current, and resistance.
PC Interface: Allows connection to a computer using supplied software for data logging and graphing. Data Hold: Freezes the current reading on the display.
Analog Bargraph: Provides a visual representation of input magnitude relative to the full scale. Technical Specifications Limit / Range DC Voltage Up to 1,000V AC Voltage Up to 750V Current (DC/AC) Resistance Up to 40 M Ωcap omega Safety Rating CAT II (600V) Operating Instructions
For detailed operational steps, you can view the Radio Shack Digital Multimeter Manual on Scribd or access the full text archive at the Internet Archive.
Preparation: Press the latch to open the case and remove the test leads.
Connections: Plug the Black lead into the COM jack and the Red lead into the V/$\Omega$/mA or 20A jack, depending on the measurement.
Selection: Rotate the function switch to the desired measurement (e.g., DC Voltage for batteries).
Measurement: Connect the probes in parallel for voltage or in series for current.
Data Logging: Use the RS-232 Connectivity documentation from sigrok to interface with modern software. Safety Warnings
Full text of "radio shack meters support 64777" - Internet Archive
Feature: Auto-Ranging with True RMS Measurement
Description: The RadioShack 24 Range Digital Multimeter 22-805 is an advanced multimeter that features auto-ranging capabilities and True RMS (Root Mean Square) measurement. This feature allows users to easily measure a wide range of electrical parameters, including AC/DC voltage, current, resistance, and more.
Benefits:
Technical Specifications:
Potential Applications:
Overall, the RadioShack 24 Range Digital Multimeter 22-805 is a versatile and accurate tool that can be used in a variety of applications, from basic troubleshooting to advanced electronics work. Its auto-ranging and True RMS measurement features make it an ideal choice for professionals and DIYers alike.
The RadioShack 22-805 is a versatile, 24-range digital multimeter (DMM) designed for field, lab, and home use. Known for its durable build and 3¾-digit LCD display, it remains a reliable tool for measuring voltage, current, and resistance with high precision. Key Features and Specifications
The 22-805 model stands out with its ability to display up to 3,999 units (4,000 counts) and its inclusion of a computer interface for advanced data logging.
Display: 3¾-digit LCD with an analog bargraph to show measurement magnitude relative to the full scale.
Computer Interface: RS-232 serial connectivity allows users to log and graph measurements on a PC using original MS-DOS or early Windows software.
Auto-Ranging: Features automatic range selection with a manual-ranging override for specific testing needs.
Data Hold: Temporarily freezes the displayed value for easy reading after disconnecting the probes.
Safety Rating: CAT II rated for up to 600V; the meter is protected by double insulation. Measurement Type Maximum Range DC Voltage AC Voltage DC/AC Current Resistance Operating Instructions
Before using the meter, ensure you are familiar with the Safety Precautions to prevent injury or equipment damage. 1. Measuring Voltage
Plug the black test lead into the COM (Common) jack and the red lead into the V/Ω/mA jack.
Set the function selector to the desired DCV or ACV position.
Touch the probes to the circuit in parallel. The meter will automatically select the best range for the reading.
Read the value on the LCD display; the analog bargraph will indicate the level of voltage relative to the range. 2. Measuring Resistance
Important: Turn off all power to the circuit and discharge any capacitors before testing. Set the selector dial to the Ω (Ohm) position.
Touch the probes to the component. If the component is part of a circuit, it should be isolated for an accurate reading.
Title: The Keeper of the Ohms
The basement of the old industrial complex was a graveyard of forgotten technology. Elias, a contractor who specialized in restoring pre-war electronics, moved a heavy wooden crate aside, coughing in the dust. He wasn't supposed to be here, but the client had been desperate to find the control module for a defunct heating system, and the blueprints said it was buried here somewhere. radio shack 24 range digital multimeter 22-805 manual
His hand brushed against a hard, rectangular object wedged between two rusted fuse boxes. He pulled it out. It was a faded yellow and black carrying case, the logo on the front reading Radio Shack in peeling letters.
Elias unzipped the case. Inside, resting in a bed of gray foam that was slowly turning to dust, lay the device: a Radio Shack 22-805 24-Range Digital Multimeter.
It was a relic from a different era of troubleshooting. The LCD screen was protected by a slightly yellowed plastic window, and the rotary dial felt heavy and substantial as he thumbed it. The device was intact, but Elias knew better than to trust old gear blindly. He needed the instructions, the secret code to unlocking the tool's potential without frying the circuit he was trying to save.
He checked the pouch on the lid. Empty.
"Of course," he muttered. He pulled his smartphone from his pocket, intending to search for a PDF, but the thick concrete walls showed zero signal bars. He was on his own.
He looked back at the 22-805. It was a robust machine—famous for its fused current protection and the ability to measure both capacitance and temperature with the right attachments. But without knowing the specific jack configurations for the 10 Amp versus the 200mA fused inputs, a wrong guess could blow the internal fuse instantly.
He sat on an overturned bucket and studied the faceplate. The legends were worn. He needed the manual.
Elias wasn't just a fixer; he was a scavenger. He looked at the carrying case again. There was a false bottom in the foam. He dug his fingers into the padding, tearing away the brittle foam, until he felt the crinkle of paper.
His heart did a small skip. He pulled out a tri-folded, slightly oil-stained booklet. The cover read: Owner’s Manual - 24-Range Digital Multimeter 22-805.
He unfolded it on his knee. The text was small but legible.
"Step one," he whispered to the silence of the basement.
He scanned the pages. He found the section on DC Current Measurement. The manual was precise, written in that classic, no-nonsense Radio Shack instructional style.
Elias looked at the dusty heating module. He suspected the solenoid was drawing too much current, tripping the breaker. He needed to measure the draw.
He wiped the test leads on his jeans. He plugged the black lead into COM. He paused, looking at the manual again. The schematic in the booklet showed exactly where the fuse was located—a 200mA fast-blow fuse (Type F).
He set the dial to the 200mA setting, plugged the red lead into the VΩmA jack, and hooked the meter in series with the solenoid.
The LCD flickered to life, the backlight a ghostly green in the dim basement.
The numbers climbed. 50mA... 100mA... 150mA... The RadioShack 24-Range LCD Digital Multimeter (Cat
Suddenly, the meter beeped, the screen flashed, and the reading dropped to zero.
"Fuse," Elias said, clicking his tongue.
He opened the battery compartment on the back of the 22-805. The manual’s diagram was perfect—it showed the exact location of the fuse carrier. He pulled the blown glass tube. It was a standard 200mA fuse.
He didn't have a replacement. But the manual had taught him something else: the 10A range was unfused, designed for heavy lifting, though only for short durations.
He consulted the booklet again. Warning: Do not make current measurements on the 10A scale for longer than 15 seconds.
"Alright, let's be quick," he said.
He moved the red lead to the 10A jack, turned the dial to the 10A setting, and connected the circuit again. This time, the reading held steady.
5.4 Amps.
The module was rated for 2 Amps. He had found the fault. The solenoid coil was shorted internally. He didn't need the module; he needed a new motor.
Elias packed up the meter. He carefully folded the manual and placed it back into the case. That piece of paper was more valuable than the tool itself. Without the manual, he would have been guessing at the jacks, likely blowing a fuse he couldn't replace, and leaving the basement without an answer.
He zipped the yellow case shut. The Radio Shack 22-805 had done its job, bridging the gap between a forgotten basement and a solved mystery, guided by the words on a single, oil-stained piece of paper.
He climbed the stairs, the weight of the multimeter in his pocket a comforting reminder that sometimes, the old ways—and the instructions that came with them—were still the best.
The RadioShack 22-805 is a basic, non-CAT rated meter. Do not use it on high-energy circuits (main breaker panels, industrial equipment, 480V systems). It’s excellent for:
For modern house wiring or complex troubleshooting, invest in a modern multimeter with a CAT III safety rating.
"Radio Shack 22-805 manual" at ManualsLib or Archive.org).From top (12 o’clock) counter-clockwise:
Due to Radio Shack’s bankruptcy and restructuring, you cannot request a manual from the company directly. However, the manual is preserved in several online archives.
Without the 22-805 manual, you will eventually blow the internal 500mA fuse. It’s a rite of passage. But here is what the yellow-and-black stapled booklet tells you that the internet forgets: AC/DC voltage (up to 600V) AC/DC current (up