Icom Ci V Usb Interface Schematic Top -

| Component | Value / Part | Quantity | |--------------------|------------------------|----------| | UART bridge | FT232RL or CH340G | 1 | | Optocoupler (fast) | 6N137 or PC900 | 2 | | NPN transistor | 2N3904 / 2N2222 | 1 | | Resistor kit | 330Ω, 560Ω, 1k, 2.2k, 4.7k, 10k | each | | Capacitors | 0.1µF, 10µF (electrolytic) | few | | 3.5mm TRS jack | Stereo, PCB mount | 1 | | USB connector | USB-B or micro-USB | 1 | | Ferrite beads | 600Ω @ 100MHz | 2 | | 78L05 regulator | (if radio provides >5V) | 1 (opt) |

If you prefer a ready-made product, several commercial interfaces appear at the top of search results, including:

However, building from a top-quality schematic gives you complete control over isolation quality, component choice, and cost (under $15). icom ci v usb interface schematic top

Board size: ~40×20 mm (e.g., similar to a CP2102 breakout)

Top side components (from left to right assuming USB connector on left edge): | Component | Value / Part | Quantity

| Region | Component | Label / Value | |--------|-----------|----------------| | Left edge | USB mini‑B or USB‑C | J1 (USB input) | | Next | USB‑to‑UART IC | CP2102 (QFN‑28) or CH340G (SOP‑16) | | Next | 3.3V regulator (if needed) | AMS1117‑3.3 (SOT‑223) | | Center‑right | Dual transistor / inverter | 2N7002 (x2) or BC547 (x2) or IC like 74HC05 (open‑drain) | | Right edge | 3‑pin header | J2: Tip (DATA), Ring (GND), Sleeve (optional +5V) → to 3.5mm TRS jack (Icom CI‑V plug) |

Top copper traces (conceptual):

If you are drawing your own top-level schematic in KiCad:

Best for: Builders using older laptops with serial ports or standard RS-232 to USB adapters. Common Chips: MAX232, MAX233. However, building from a top-quality schematic gives you

This was the standard design in the 1990s and 2000s. It converts USB to RS-232 voltages (+/- 12V), and then converts that back down to TTL for the radio.

The Schematic Stages:

USB Type-B              USB-to-UART             Level Shifter           CI-V (to radio)
─────────              ──────────────          ─────────────            ─────────────
VBUS ────────────────► VCC (5V)
                      │
D+ ──────────────────► USBD+ (FTDI/CP2102)
D- ──────────────────► USBD-
                      │
GND ──────────────────► GND
                      │
                      TXD ──────────┬──────────► Level Shifter (e.g., 2N7000 or MAX232)
                      RXD ◄─────────┼──────────►
                      │             │
                      └─── 10k pull-up to 5V ──┐
                                               │
                                          ┌────┴────┐
                                          │ 2N7000  │
                                          │ MOSFET  │
                                          └────┬────┘
                                               │
                         CI-V Data ────────────┘ (Open collector)
                         (3.5mm jack tip)
                         GND ─────────────────── (sleeve)