Product Overview
National Semiconductor LM301AN Precision Op Amp, Unused NOS in an 8-Pin Plastic DIP
Condition
Unused, New Old Stock. The photographed piece is a black plastic 8-pin DIP with the National Semiconductor NS logo and the characters /621 across the top line and LM301AN printed below it, plus the molded pin 1 dimple to the left of the marking. All eight leads are straight and bright, with no solder, no flux residue, and no bend marks. The ink is crisp and the body shows only its normal molding seam. Against the millimeter ruler in the photo the plastic body measures approximately 9 mm long, the standard 8-pin DIP footprint. Shown resting on pink anti-static wrap. Stock on hand is five pieces.
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Product Overview
The LM301AN is the commercial-grade plastic DIP member of National Semiconductor's LM101A / LM201A / LM301A precision operational amplifier family, and it is the part that vintage analog schematics call out by name. It pairs low input offset voltage and controlled input bias current with offset-null pins for hand trimming, and it runs on dual supplies from +/-5 V to +/-18 V, which is why it turned up so often in audio stages, bench test equipment, and analog control assemblies. The through-hole DIP-8 body drops into an existing socket or board, and the top marking on this piece is legible enough to check against an original bill of materials before you commit to the repair. Related numbers you may see in old documentation include LM101A and LM201A, which are the same design in different temperature grades.
Key Features
- Single-channel precision operational amplifier in an 8-pin plastic DIP
- Input offset voltage typically around 2 to 7 mV depending on conditions
- Input bias current in the tens to hundreds of nanoamps
- Large-signal voltage gain reaching well over 25 V/mV
- Gain-bandwidth product in the low single-digit MHz range with the recommended compensation
- Slew rate on the order of 0.5 V per microsecond
- Dual supply operation from +/-5 V to +/-18 V
- Offset-null pins 1 and 5 for manual trimming
- Top marked with the NS logo, the characters /621, and LM301AN
The electrical figures above come from family datasheet literature and were not measured on this unit. Not confirmed here - verify against the datasheet before use.
Applications
- Bench technician rebuilding an active filter stage in a 1970s instrumentation chassis and wanting the original part number back in the socket
- Audio restorer replacing a failed op amp in a vintage mixer or preamp without redesigning the stage around a modern single-supply device
- Lab engineer breadboarding an integrator or summing amplifier on a DIP-8 prototype board running split supplies
- Instructor or student demonstrating classic externally compensated op amp behavior on real hardware instead of a simulation
Frequently Asked Questions
What do pins 1 and 5 do on this part?
They are the offset-null pins. A trim pot across them lets you center the output when your circuit needs tighter DC accuracy than the untrimmed offset voltage gives you.
How is the LM301AN compensated?
The 301A family is built for external compensation: a small capacitor sized for your closed-loop gain, with the recommended unity-gain value given in the datasheet. Choose the value for your gain and verify it against the datasheet before use.
What supply rails does it expect?
Dual supplies from roughly +/-5 V to +/-18 V, which matches the legacy analog systems this part was designed into. It is not a single-supply rail-to-rail device.
Will it drop into a circuit built around a modern rail-to-rail op amp?
Usually not. Its input and output swing reflect 1970s analog topology, so a board designed around a modern single-supply part may not behave the same way. Going the other direction, back into an original 301A socket, is exactly what this piece is for.
I only need two for one board. Why buy them here instead of a bulk tube?
Because a repair needs the count that actually goes into the board, plus maybe one spare, and nothing after that. We have five of these on the shelf and sell them one at a time, so you can take two and stop, instead of paying for a tube of 25 that lives in a drawer forever. Shipping is $8 flat rate and free once your order passes $28, and orders leave our Idaho warehouse the same or next business day.
The 301A is the op amp that handed the compensation capacitor back to the designer, and the NS logo stamped on this one still looks the way it did the day it left the fab. Pick your capacitor, set your gain, and put it back to work in the board that has been waiting on it.
