Product Overview
Motorola 6-124C45 Carbon Composition Resistor File Card - 680 Ohm 1/4W 10% Tolerance, 10 Units NOS
Condition
Unused NOS. Ten resistors seated in the original Motorola file card. Tab markings 6-124C45 and 680-10-1/4 are legible. Reverse of card is printed 54-84066A05 and PRINTED IN U.S.A. Card shows edge wear and scuffs consistent with storage. Brown-bodied resistors display blue-gray-brown-silver band configuration with silver end-cap terminations. Sourced from an electronics distributor consolidating inventory.
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Product Overview
Motorola 6-124C45 - a file card pack of 10 carbon composition resistors, 680 ohm, 1/4 watt, 10% tolerance. Packaged in Motorola's original tabbed file card format with stamped specifications and an EIA color code chart on the reverse. Carbon composition construction gives these resistors the noise character and pulse-handling behavior that vintage audio and radio restorers specifically seek out when modern metal film parts fall short of period-correct results.
Key Features
- Resistance: 680 ohm
- Power rating: 1/4 watt
- Tolerance: 10%
- Type: Carbon composition
- Quantity: 10 resistors per card
- Band configuration: Blue-gray-brown-silver (confirmed by visible markings)
- Part number on card tab: 6-124C45; alternate reference on reverse: 54-84066A05
- Card printed PRINTED IN U.S.A. with EIA color code chart on reverse panel
- Unused NOS - never removed from original file card
Applications
- Replacing a drifted or failed grid or plate resistor in a vintage tube amplifier while keeping the build period-correct - carbon composition matters here because metal film changes the noise floor and some builders say the tone along with it
- Swapping a failed resistor in a vintage ham radio transceiver or receiver to restore it to operational status without substituting modern parts that alter the original circuit character
- Sourcing a small quantity of NOS carbon comp resistors for a boutique guitar amp build targeting the sound of early hand-wired designs
- Stocking a repair bench with period-correct 680 ohm values for ongoing vintage electronics work - having a full card of 10 on hand avoids single-unit delays mid-repair
- Makers and experimenters who want genuine vintage carbon comp behavior in a custom circuit - lower precision than metal film, but that characteristic noise texture is sometimes exactly the point
Frequently Asked Questions
Are these carbon composition or carbon film resistors?
Carbon composition. The research notes and visible brown-bodied construction with blue-gray-brown-silver banding confirm carbon composition type. Carbon film is a different construction and produces different noise and pulse characteristics - if you need the carbon comp sound or behavior specifically, these are the correct type.
What does the 10% tolerance mean for my application?
Each resistor may measure anywhere from 612 ohm to 748 ohm and still be within spec. For vintage audio and radio restoration in circuits originally designed around 10% carbon comp parts, that is exactly what was intended. High-precision or low-noise applications calling for tighter tolerances should use metal film resistors instead.
Is the full card of 10 included?
Yes. You receive the complete Motorola file card with all 10 resistors seated in the card window, as shown in the product photos.
Do carbon composition resistors degrade in storage?
Carbon composition resistors can absorb moisture over time, which may cause resistance to drift. These are unused NOS parts stored dry. Measuring each resistor before installation is standard practice for vintage restoration work.
Ten little brown cylinders on a Motorola card that outlasted the era that made them - still wound tight, still reading blue-gray-brown-silver, still ready to do the job they were made for. Whatever bench they land on next, they come with the right number.
