Rc Filter

{
  "angularCutoffRadS": 1000,
  "asOf": "2026-10-11T08:33:12.513Z",
  "capacitanceF": 1.0000000000000001e-7,
  "chargeTimesS": {
    "p632": 0.001,
    "p90": 0.0023025851,
    "p95": 0.0029957323,
    "p99": 0.0046051702,
    "p999": 0.0069077553
  },
  "cutoffHz": 159.15494,
  "degraded": false,
  "disclaimer": "Screening signal computed from the named public source. Not financial, legal or investment advice; provided as is. Verify at the source before acting.",
  "formatted": {
    "cutoff": "159.2 Hz",
    "tau": "1 ms"
  },
  "notChecked": [
    "source and load impedance (they shift the real cutoff)",
    "capacitor tolerance, ESR and voltage derating",
    "…1 more"
  ],
  "reasons": [
    "Cutoff fc = 1 / (2 pi R C): a low-pass passes below it and a high-pass passes above it, -20 dB per decade.",
    "Charge to 63.2% in 1 tau, 86.5% in 2, 95% in 3, 98.2% in 4, 99.3% in 5."
  ],
  "resistanceOhm": 10000,
  "source": "computed locally",
  "summary": "R=10 kohm, C=100 nF: time constant 1 ms, cutoff (-3 dB) 159.2 Hz; 99% charged in 4.605 ms.",
  "timeConstantS": 0.001,
  "verdict": "COMPUTED"
}

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i 'https://electronics-calc.x402tookit.com/rc-filter?capacitance=100n&resistance=10k'

# x402 v2 sends the challenge base64-encoded in the PAYMENT-REQUIRED header (v1 sends it in the body).
# To read the header:
curl -sS -g -o /dev/null -D - 'https://electronics-calc.x402tookit.com/rc-filter?capacitance=100n&resistance=10k' \
  | grep -i '^payment-required:' | cut -d' ' -f2 | tr -d '\r' | base64 --decode

// npm i @x402/fetch @x402/evm viem
import { wrapFetchWithPayment, x402Client } from "@x402/fetch";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

// Pays at most $0.02 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.02" });
registerExactEvmScheme(client, { signer: privateKeyToAccount(process.env.EVM_PRIVATE_KEY) });
const pay = wrapFetchWithPayment(fetch, client);

// Not sure it's safe to pay? ToolVet checks it first for $0.005. Pay for that from a separate
// client: this one is capped at $0.02 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2Felectronics-calc.x402tookit.com%2Frc-filter
const res = await pay("https://electronics-calc.x402tookit.com/rc-filter?capacitance=100n&resistance=10k");
console.log(res.status, await res.text());

# pip install "x402[requests,evm]"
import os
from eth_account import Account
from x402 import x402ClientSync
from x402.http.clients import x402_requests
from x402.mechanisms.evm import EthAccountSigner
from x402.mechanisms.evm.exact.register import register_exact_evm_client

# Pays at most $0.02 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.02"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))

with x402_requests(client) as session:
    res = session.get("https://electronics-calc.x402tookit.com/rc-filter?capacitance=100n&resistance=10k")
    print(res.status_code, res.text)