R/C Decade Boxes
A decade box lets you dial a resistance or a capacitance in and measure what the circuit does, instead of soldering a part, testing, desoldering and trying the next one. Use one when you are finding a value rather than fitting one — setting a gain, tuning a time constant, checking how sensitive a design is to a component you have not chosen yet. These are manual instruments with switches on the front, not programmable sources.
ATI stocks three: a resistor box covering 0.1 Ω to 100 MΩ, a capacitor box covering 1 pF to 100 µF, and a combined unit with both in one enclosure. All are switch-selected with a readable front panel and a metal case, and priced from $79.
The boxes
Three units. The choice is whether you need resistance, capacitance, or both, and then whether range or convenience matters more — the dedicated boxes reach considerably further at each end than the combined unit does. The table below sets that out.
Showing all 3 resultsSorted by price: low to high
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Adjustable Capacitor Decade Box ATCDB12
$79.00 -
Adjustable Resistor Decade Box ATRDB12
$79.00 -
Variable Resistor & Capacitor Box ATRCT101
$99.00
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Which box do I need?
Two dedicated boxes with wide range, or one combined unit that does both over a narrower span.
| Model | Resistance | Capacitance | Resolution | Price | Choose this if… |
|---|---|---|---|---|---|
| ATRDB12 Resistor decade box | 0.1 Ω – 100 MΩ | — | 0.1 Ω | $79 | Resistance is what you are hunting for. Widest range here by a long way, down to 0.1 Ω and up to 100 MΩ, at 1 % accuracy. |
| ATCDB12 Capacitor decade box | — | 1 pF – 100 µF | 1 pF | $79 | You are tuning filters, timing or compensation. 1 pF steps at the bottom end matter for RF and oscillator work. |
| ATRCT101 Combined R and C | 1 Ω – 1000 kΩ | 10 pF – 10 µF | 1 Ω / 10 pF | $99 | You want both on one bench without buying two instruments, and your values sit in the middle of the range rather than at the extremes. |
Worth knowing
- The combined unit trades range for convenience. ATRCT101 covers 1 Ω to 1000 kΩ where the dedicated resistor box goes from 0.1 Ω to 100 MΩ, and 10 pF to 10 µF where the dedicated capacitor box goes from 1 pF to 100 µF. If your work lives at either extreme — milliohm shunts, megohm bias networks, picofarad matching — buy the dedicated box.
- Two dedicated boxes cost $158, the combined unit $99. The saving is real, but so is the range you give up. Worth checking your typical values against the table above before deciding on price alone.
- Resolution is the smallest step, not the accuracy. A box that steps in 0.1 Ω increments still carries a percentage tolerance on whatever value you dial, and at the bottom of the range the resistance of the leads and switch contacts is part of what your circuit sees.
Why buy these from ATI
- Both instruments at $79 — Prices are published and there is no quote to request. A decade box is a tool you buy once and use for years, and these are priced as bench equipment rather than as laboratory instruments.
- Readable panel, metal case — Built to sit on a bench and be used, with a front panel you can read at a glance while adjusting.
- They pair with the kits — Dial the value in here, then take the part out of a resistor or capacitor kit and fit it. That is the whole workflow, and both halves come from the same place.
- Ships from San Jose — In stock and out the door in a day or two.
Frequently asked questions
Should I buy a decade box or a component kit?
They solve different halves of the same job. A decade box is for finding the value: turn the switches, watch the circuit respond, converge on a number in a few minutes without touching a soldering iron. A kit is for fitting it once you know. Most benches end up with both, because a decade box cannot stay in the circuit and a kit cannot be swept through fifty values in five minutes.
Can I leave a decade box connected in a working circuit?
Only while you are testing. These are bench instruments, not components: current has to pass through switch contacts and lead wires that a soldered part does not have, and the contact resistance and stray capacitance that come with that are fine for evaluation and wrong for permanent installation. Once you have the value, fit a real part.
Why is the value my meter reads slightly off the dialled setting?
Several things add up in normal use. Leads and switch contacts contribute a small resistance of their own, which matters most when you are dialling low values — at a setting of a few ohms it can be a noticeable share of the total. On the capacitance side, lead and fixture capacitance adds to whatever you have selected, which is most visible at the picofarad end. Measure the leads shorted or open first and treat that as your baseline.
Are these programmable?
No. The values are set by hand with switches on the front panel, which is what keeps them at this price and makes them quick to use for interactive work. If you need a value stepped automatically as part of a test sequence, you want a programmable source instead.