RC transient
API · /capacitor-api
Capacitor API
healthy
3,975 Subscribers
Capacitor maths as an API, computed locally and deterministically. The energy endpoint computes the stored energy and charge of a capacitor from any two of the capacitance, the voltage and the charge — E = ½CV² = ½QV and Q = CV — in joules, millijoules and coulombs. The charging endpoint models the RC charging and discharging transient: the time constant τ = RC, the voltage at a given time, V(t) = Vs(1 − e^(−t/RC)) when charging or V(t) = V₀·e^(−t/RC) when discharging, and the percent charged, or — given a target voltage — the time to reach it; a capacitor reaches about 63 % of the way in one time constant and over 99 % in five. The combination endpoint computes the total capacitance of capacitors in series (1/C = Σ1/Cᵢ) or parallel (C = ΣCᵢ). Capacitance accepts farads or the handy µF/nF/pF units. Everything is computed locally and deterministically, so it is instant and private. Ideal for electronics, maker, embedded and circuit-design app developers, power-supply and timing tools, and electronics education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is capacitor maths; for AC reactance and resonance use a resonance API and for LED resistor sizing an LED-resistor API.
api.oanor.com/capacitor-api
API health
healthy- Uptime
- 100.00%
- Server probes · 24h
- Avg latency
- 79 ms
- Server probes · 24h
- Subscribers
- 3,975
- active
- Total calls
- 80
- last 7 days
Pricing
Pick a tier — billed monthly, cancel anytime.
Free
Free
- 2,000 calls / month
- 2 requests / second
- Hard cap (429 above quota, no overage)
- Energy & charge from any two of E, C, V, Q
- Deterministic local compute, sub-ms response
- 2,000 calls/month for prototyping
Starter
€9.00 /month
- 20,000 calls / month
- 5 requests / second
- Hard cap (429 above quota, no overage)
- All capacitor energy & charge formulas
- RC time-constant (tau) endpoint
- 20,000 calls/month for maker projects
- SI unit handling, no rounding drift
Pro
€24.00 /month
- 120,000 calls / month
- 15 requests / second
- Hard cap (429 above quota, no overage)
- Full RC charge/discharge curve solving
- Series & parallel capacitance reduction
- 120,000 calls/month for production tools
- Priority throughput at 15 rps
Mega
€74.00 /month
- 600,000 calls / month
- 40 requests / second
- Hard cap (429 above quota, no overage)
- Unlimited capacitor & RC endpoints
- High-volume batch-friendly 40 rps
- 600,000 calls/month for EDA/CAD backends
- Best per-call rate for embedded use
Built by
Related APIs
Other APIs with overlapping tags.
Newegg API
Live product search from Newegg.com, the major electronics & tech retailer. Search any keyword — laptop, rtx 4070, ssd — and get the product listings with title, brand, model, current price, original price, image, rating, review count, in-stock status, seller and the Newegg product URL. Prices are live USD. Ideal for shopping, price-comparison, deal-tracking and e-commerce dashboards.
api.oanor.com/newegg-api
RTD Pt100 Sensor API
RTD (resistance-temperature-detector) sensor maths as an API, computed locally and deterministically with the IEC 60751 Callendar–Van Dusen equation — the resistance, temperature and tolerance numbers an instrumentation or controls engineer reads a Pt100 or Pt1000 with. The resistance endpoint gives the sensor resistance from temperature: above 0 °C, R = R₀·(1 + A·T + B·T²) with A = 3.9083×10⁻³ and B = −5.775×10⁻⁷; below 0 °C a third term adds C·(T−100)·T³ — a standard Pt100 (100 Ω at 0 °C) reads 138.51 Ω at 100 °C and 80.31 Ω at −50 °C, and a Pt1000 is ten times that. The temperature endpoint inverts it to turn a measured resistance back into temperature — analytically above 0 °C, iteratively below — exactly what a transmitter does with the bridge reading, and a reminder that a 3- or 4-wire connection cancels the lead-wire resistance so it does not read as extra degrees. The tolerance endpoint gives the IEC 60751 accuracy band in both °C and Ω by class — AA ±(0.10 + 0.0017·|T|), A ±(0.15 + 0.002·|T|), B ±(0.30 + 0.005·|T|), C ±(0.60 + 0.010·|T|) — the error growing with distance from 0 °C. Everything is computed locally and deterministically, so it is instant and private. Ideal for instrumentation and controls software, data-logger and transmitter firmware, calibration and industrial-IoT tools. Pure local computation — no key, no third-party service, instant. 3 compute endpoints. For NTC thermistors use a thermistor API; for thermocouples a thermocouple API.
api.oanor.com/rtd-api
Voltage Divider API
Resistive voltage-divider circuit design as an API, computed locally and deterministically. The divide endpoint takes an input voltage and two resistors and returns the output voltage Vout = Vin·R2/(R1+R2), the current I = Vin/(R1+R2) that flows through the chain, and the power dissipated in each resistor and in total — a 12 V source with R1 = 1 kΩ and R2 = 2 kΩ gives 8 V at 4 mA. The loaded endpoint adds a load resistor across R2, computes the parallel combination R2′ = R2·RL/(R2+RL) and the loaded output Vout = Vin·R2′/(R1+R2′), and reports the droop in volts and percent against the unloaded value, the classic mistake when a divider feeds a real load. The resistor endpoint sizes the missing resistor for a target output — R2 = R1·Vout/(Vin−Vout) or R1 = R2·(Vin−Vout)/Vout — so you can pick parts for a reference or sensor-bias point. All quantities are volts, ohms, amps and watts. Everything is computed locally and deterministically, so it is instant and private. Ideal for electronics, embedded, hardware, sensor-interfacing and EE-education app developers, reference-voltage and bias-network tools, and maker software. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is the resistive divider; for a single Ohm’s-law relationship use an Ohm’s-law API and for RC/RL filters an RC-filter API.
api.oanor.com/voltagedivider-api
RC Filter API
First-order RC and RL passive-filter design as an API, computed locally and deterministically. The lowpass and highpass endpoints take a resistor and capacitor (RC) or a resistor and inductor (RL) and return the −3 dB cutoff frequency (fc = 1/(2πRC) for RC, R/(2πL) for RL), the time constant (τ = RC or L/R) and the angular cutoff; pass a frequency as well and they add the magnitude response as a linear gain and in decibels and the phase shift in degrees — a 1 kΩ / 1 µF low-pass has fc ≈ 159.15 Hz, and right at the cutoff the gain is −3.01 dB with −45° phase for a low-pass or +45° for a high-pass. The component endpoint solves the missing one of fc, R and C from the other two (fc = 1/(2πRC)), so you can size a resistor or capacitor for a target cutoff. All quantities are SI: ohms, farads, henries and hertz. Everything is computed locally and deterministically, so it is instant and private. Ideal for electronics, audio, embedded, signal-processing and EE-education app developers, filter-design and circuit-sizing tools, and maker software. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is first-order single-pole filter design; for full RLC impedance and resonance use an impedance API and for stored capacitor energy a capacitor API.
api.oanor.com/rcfilter-api
Frequently asked questions
Quick answers about pricing, quotas, and integration.
How do I get an API key for Capacitor API?
Sign up for free at oanor.com, generate an API key from the developer dashboard, and call Capacitor API with the x-oanor-key header. No credit card needed for the free tier.
What's the rate limit for Capacitor API?
Free tier allows 1 request per second. Paid plans scale up to 50 requests per second on the Mega tier. Hard limits return HTTP 429 above the quota — no surprise overage charges.
How much does Capacitor API cost?
Capacitor API has a free tier with 100 calls / month. Paid plans start at €9.00 / month with higher quotas and faster rate limits.
Can I cancel my subscription anytime?
Yes. Plans are billed monthly and you can cancel anytime from your billing dashboard. No long-term contracts and no cancellation fee.
Is Capacitor API GDPR-compliant?
All requests to Capacitor API go through our EU-based gateway. Your upstream API key never leaves our server and no personal data is shared with the upstream provider beyond the request you send.
Pick an endpoint from the list on the left to see its details and try it.
Code snippets
Sign up to get an API key, then call any path under your slug.
curl https://api.oanor.com/capacitor-api/SOME_PATH \
-H "x-oanor-key: oanor_test_..."const res = await fetch("https://api.oanor.com/capacitor-api/SOME_PATH", {
headers: { "x-oanor-key": "oanor_test_..." }
});
const data = await res.json();$ch = curl_init("https://api.oanor.com/capacitor-api/SOME_PATH");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, ["x-oanor-key: oanor_test_..."]);
$response = curl_exec($ch);import requests
r = requests.get(
"https://api.oanor.com/capacitor-api/SOME_PATH",
headers={"x-oanor-key": "oanor_test_..."},
)
print(r.json())Ratings
Sign in to rate.
No reviews yet.
Discussion
Ask questions, share usage tips, get answers from the provider and other developers. Public — anyone can read.
Sign in to start a thread or reply.
Sign inNew thread
📌 Pinned
🔒 Locked
·
·
·
-
Provider answer
🔒 This thread is locked — no new replies.
-
·
- No threads yet — start the discussion.
Support
Private 1:1 support with the provider — billing questions, integration issues, account problems. Only you and the provider team can see these threads.
Sign in to open a support ticket.
Sign inOpen new ticket
Describe what you need help with. The provider team gets an email and replies on the ticket page.
-
·
Urgent - No tickets yet for this API.