1S5
1S5 is also designated DAF91. Completed sales put the typical price at $12.60 per tube.
Description
The 1S5 is a miniature tube containing a diode and a sharp-cutoff pentode, designed for use as a combined detector and audio-frequency voltage amplifier in compact battery-operated equipment. It has a coated filament cathode and a T-5 1/2 glass envelope with an E7-1 miniature button 7-pin base. The mounting position is direct.
Filament Ratings
The filament voltage is 1.4 volts D-C, and the filament current is 0.05 ampere.
Pin Assignments
Pin 1 is negative filament and grid number 3. Pin 3 is diode plate. Pin 4 is grid number 2 (screen). Pin 5 is plate. Pin 6 is grid number 1. Pin 7 is positive filament.
Ratings and Characteristics
The average diode current rating is 0.25 milliampere for continuous operation. The S1 datasheet gives maximum plate voltage of 90 volts, maximum screen voltage of 90 volts, and maximum total cathode current of 3 milliamperes for the 1S5.
At 67.5 volts plate voltage, the 1S5 has a plate resistance of approximately 0.6 megohm, a transconductance of 625 micromhos, a plate current of 1.6 milliamperes, and a screen current of 0.4 milliampere. The grid number 1 voltage is approximately -5 volts for a plate current of 10 microamperes.
| Designation | Evidence | Confidence |
|---|---|---|
| DAF91 | 50 independent documents | confirmed |
Equivalence is asserted only where the archive's own literature states it directly, in at least 40 separate documents. Tubes that merely substitute in some circuits are not listed here.
| Measure | Per tube |
|---|---|
| Median | $12.60 |
| Typical range (25th–75th) | $7.50 – $18.99 |
| Most sales (10th–90th) | $5.00 – $28.41 |
| Extremes incl. outliers | $5.00 – $50.01 |
| Completed sales | 15 |
| Brand | Median | Range | Sales |
|---|---|---|---|
| RCA | $11.65 | $7.50 – $12.60 | 3 |
| Condition | Median | Sales |
|---|---|---|
| NOS | $11.10 | 10 |
| used | $27.20 | 3 |
Per-tube prices from completed sales, 2026-06-13 to 2026-09-01. Matched pairs and quads are divided out. See the price index for how these move over time.
Original manufacturer datasheets for 1S5, hosted by Frank Philipse's Electron Tube Data sheets.
| Manufacturer | Designation | Datasheet |
|---|---|---|
| General Electric | 1S5 | PDF (402 KB) |
| Mazda-Belvu | 1S5 | PDF (319 KB) |
| Tung-Sol | 1S5 | PDF (221 KB) |
| Brimar | 1S5 | PDF (91 KB) |
| Philips | DAF91 | PDF (449 KB) |
| Mullard | DAF91 | PDF (276 KB) |
| Philips | DAF91 | PDF (252 KB) |
| Mullard | DAF91 | PDF (149 KB) |
Documents held here and used to write this page.
- "Miniwatt" DAF 91 (filed under DAF91)
- Description and Rating
2 further designations appear alongside 1S5 in the literature but below the evidence threshold used here, so they are not listed as equivalent.