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CFR25J 1M0 Resistor - Full Specifications & Use Cases | Communica South Africa

Overview: What is the CFR25J 1M0 Resistor?

The CFR25J 1M0 is a widely-used carbon film resistor offering a resistance value of 1 megaohm (1MOhm), with a power rating tailored for general-purpose through-hole applications. It belongs to the CFR25J series, which is popular throughout South African educational, industrial, and hobbyist circuits due to good reliability, consistent sourcing, and competitive pricing.

Understanding the full specification helps in choosing the right resistor for biasing, pull-up/down, and analog filter circuits. Local branches-such as Communica Samrand and Pretoria-consistently stock these resistors for quick pickup and project continuity.

Technical Specifications of CFR25J 1M0

Property	Value	Notes
Resistance	1MOhm (1,000,000 Ohm)	Marked "1M0"
Power Rating	0.25W (1/4 watt)	Ambient 70 degreesC (derate as needed)
Tolerance	5% (J)	"J" code for 5%
Max Working Voltage	250V	Do not exceed for safety
Max Overload Voltage	500V	Temporary only (5s)
Temperature Coefficient	300ppm/ degreesC	Typical for carbon film
Body Size (LxD)	6.0mm x 2.2mm	Excluding leads

How to Identify CFR25J 1M0 Resistors

Colour Code: Brown-Black-Green-Gold (1MOhm 5%)
Markings: Part code sometimes printed (CFR25J 1M0)
Lead spacing: ~5mm, fits standard breadboards

SA Usage Tip: Carbon film types are ideal for educational breadboarding and non-critical analogue circuits due to cost and easy colour band reading-key for large university labs and technician kits.

Typical Applications of CFR25J 1M0 Resistors

The 1MOhm value is suitable when you need a high resistance for very low current applications, voltage dividers, gate pull-ups/pull-downs, and timing circuits (RC filters/oscillators). Here are some real-world South African applications:

Breadboarding: Ideal for student project prototyping
Junction Gate Bias: Pull-up resistors for logic gates or microcontroller pins
RC Networks: Analog timing circuits (e.g., 555 timer with C = 100nF & R = 1MOhm yields ~0.1s time constant)
Input Protection: Limiting gate input current
Signal Filtering: High-pass or low-pass analogue filters

Application Example: RC Timing Circuit

Suppose you're designing a simple timer with a 555 chip for a lab demonstration. You select a CFR25J 1M0 resistor and a 1uF capacitor for your RC timing:

Formula	Calculation	Result
Time constant ()	= R x C = 1MOhm x 1uF	1 second

This is a typical scenario for timer or delay circuits in industrial or tertiary practical labs.

Selection Considerations for SA Projects

If power dissipation exceeds 0.25W, select a higher wattage type (e.g., CFR50J series)
For critical precision, consider metal film or low-temp-coefficient parts
Stock status on Communica's resistor category is updated regularly-large quantities may require special order
Bulk packs often available for education and maintenance teams
Always confirm lead spacing for automated/PCB assembly

Troubleshooting and Common Mistakes

Overheating: If a resistor is hot to the touch, recalculate power: P = (V2)/R (e.g., for 10V across 1MOhm, P = 0.0001W, well below spec)
Incorrect Placement: Double-check colour codes or marking to avoid 1Ohm or 10MOhm in error
Environmental Factors: High humidity/voltage can lead to drift; carbon film is not suitable for high-stability references

Local Note: Communica branches in Samrand, Pretoria CBD, and Cape Town allow collection of these resistors for urgent student, repair, or industry needs. VAT invoicing and quantity pricing available.

Popular Brands and Availability in South Africa

Major stocked brands: Royal Ohm, KOA Speer, Yageo, Unbranded
Availability: On-shelf singles, strips, and bulk boxes for education and industry
Related types: Metal film, 0.5W or 1W versions for higher power projects

To compare and select, visit the Resistors & Passive Components category or check branch trading hours for collection across Gauteng and Western Cape.

CFR25J 1M0 Resistor: Specifications and Practical Applications in South Africa

Key Specification Details

Application Guide

Local Sourcing Tips

Communica South Africa

Overview: What is the CFR25J 1M0 Resistor?

Technical Specifications of CFR25J 1M0

How to Identify CFR25J 1M0 Resistors

Typical Applications of CFR25J 1M0 Resistors

Application Example: RC Timing Circuit

Selection Considerations for SA Projects

Troubleshooting and Common Mistakes

Popular Brands and Availability in South Africa

Sources

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