# ISD1740 Voice Recorder ## Description ISD1740SY-based voice record/playback circuit with pushbutton controls, LED status indicator, microphone/speaker connections, oscillator/AGC network, and 5V power decoupling. ## Project Details - **Owner:** newyeork76 - **Created:** 6/9/2026 - **Last Updated:** 6/9/2026 - **Visibility:** Public ## Key Components ### D1 — [KT-0603R](https://www.flux.ai/adrian95/kt-0603r~7c.md) - Role: Indicator - Manufacturer Name: Hubei KENTO Elec - Manufacturer Part Number: KT-0603R - Role Details: Record/playback status LED - Datasheet URL: https://www.lcsc.com/datasheet/lcsc_datasheet_1810231112_Hubei-KENTO-Elec-KT-0603R_C2286.pdf - License: https://creativecommons.org/licenses/by/4.0/ - Part Type: LED **Pins:** - A [pin 2] - K [pin 1] ### J1 — [61300211121](https://www.flux.ai/adrian95/61300211121~11.md) - Manufacturer Part Number: 61300211121 - Role: Connector - Part Type: Connector - Manufacturer Name: Würth Elektronik - Datasheet URL: https://www.we-online.com/components/products/datasheet/61300211121.pdf - Role Details: 5V and GND power input - License: https://creativecommons.org/licenses/by/4.0/ **Pins:** - P1 [pin 1] - P2 [pin 2] ### J2 — [61300211121](https://www.flux.ai/adrian95/61300211121~11.md) - Manufacturer Name: Würth Elektronik - Part Type: Connector - License: https://creativecommons.org/licenses/by/4.0/ - Datasheet URL: https://www.we-online.com/components/products/datasheet/61300211121.pdf - Manufacturer Part Number: 61300211121 - Role: Connector - Role Details: MIC+ and MIC- differential microphone input **Pins:** - P1 [pin 1] - P2 [pin 2] ### J3 — [61300211121](https://www.flux.ai/adrian95/61300211121~11.md) - Part Type: Connector - Manufacturer Name: Würth Elektronik - Datasheet URL: https://www.we-online.com/components/products/datasheet/61300211121.pdf - License: https://creativecommons.org/licenses/by/4.0/ - Role Details: SP+ and SP- differential speaker output - Manufacturer Part Number: 61300211121 - Role: Connector **Pins:** - P1 [pin 1] - P2 [pin 2] ### S1 — [B3U-1000P](https://www.flux.ai/adrian95/b3u-1000p~kb2.md) - Part Type: Switch - License: https://creativecommons.org/licenses/by/4.0/ - Datasheet URL: https://omronfs.omron.com/en_US/ecb/products/pdf/en-b3u.pdf - Manufacturer Name: Omron Electronics Inc-EMC Div - Role: Switch - Role Details: Active-low FT feed-through control to ground - Manufacturer Part Number: B3U-1000P **Pins:** - 1 [pin 1] - 2 [pin 2] ### S2 — [B3U-1000P](https://www.flux.ai/adrian95/b3u-1000p~kb2.md) - Role Details: Active-low PLAY control to ground - Part Type: Switch - License: https://creativecommons.org/licenses/by/4.0/ - Role: Switch - Datasheet URL: https://omronfs.omron.com/en_US/ecb/products/pdf/en-b3u.pdf - Manufacturer Name: Omron Electronics Inc-EMC Div - Manufacturer Part Number: B3U-1000P **Pins:** - 1 [pin 1] - 2 [pin 2] ### S3 — [B3U-1000P](https://www.flux.ai/adrian95/b3u-1000p~kb2.md) - Manufacturer Name: Omron Electronics Inc-EMC Div - Manufacturer Part Number: B3U-1000P - Role: Switch - Datasheet URL: https://omronfs.omron.com/en_US/ecb/products/pdf/en-b3u.pdf - Part Type: Switch - Role Details: Active-low REC control to ground - License: https://creativecommons.org/licenses/by/4.0/ **Pins:** - 1 [pin 1] - 2 [pin 2] ### S4 — [B3U-1000P](https://www.flux.ai/adrian95/b3u-1000p~kb2.md) - Role: Switch - Manufacturer Name: Omron Electronics Inc-EMC Div - Manufacturer Part Number: B3U-1000P - Datasheet URL: https://omronfs.omron.com/en_US/ecb/products/pdf/en-b3u.pdf - Part Type: Switch - Role Details: Active-low ERASE control to ground - License: https://creativecommons.org/licenses/by/4.0/ **Pins:** - 1 [pin 1] - 2 [pin 2] ### S5 — [B3U-1000P](https://www.flux.ai/adrian95/b3u-1000p~kb2.md) - Manufacturer Name: Omron Electronics Inc-EMC Div - Manufacturer Part Number: B3U-1000P - Datasheet URL: https://omronfs.omron.com/en_US/ecb/products/pdf/en-b3u.pdf - Part Type: Switch - Role Details: Active-low FWD control to ground - License: https://creativecommons.org/licenses/by/4.0/ - Role: Switch **Pins:** - 1 [pin 1] - 2 [pin 2] ### S6 — [B3U-1000P](https://www.flux.ai/adrian95/b3u-1000p~kb2.md) - Manufacturer Part Number: B3U-1000P - Manufacturer Name: Omron Electronics Inc-EMC Div - Datasheet URL: https://omronfs.omron.com/en_US/ecb/products/pdf/en-b3u.pdf - Role: Switch - License: https://creativecommons.org/licenses/by/4.0/ - Part Type: Switch - Role Details: Active-low RESET pushbutton to ground **Pins:** - 1 [pin 1] - 2 [pin 2] ### U1 — [ISD1740SYR](https://www.flux.ai/lcsc/isd1740syr~9fss.md) - Role: Voice Record/Playback IC - Manufacturer Part Number: ISD1740SYR - Manufacturer Name: NUVOTON(新唐) - JLCPCB Part Class: Extended Part - Package or Case Code: SOIC-28_L17.9-W7.5-P1.27-LS10.3-BL - Role Details: Main ISD1740SYR device; ISD1700-series pinout verified from datasheet - LCSC Part Number: C2441413 **Pins:** - ~{ERASE} [pin 25] - ~{FT} [pin 22] - ~{FWD} [pin 26] - ~{INT}/RDY [pin 27] - ~{LED} [pin 2] - ~{PLAY} [pin 23] - ~{REC} [pin 24] - ~{RESET} [pin 3] - ~{SS} [pin 7] - ~{VOL} [pin 19] - AGC [pin 18] - AnaIn [pin 9] - AUD/AUX [pin 17] - MIC- [pin 11] - MIC+ [pin 10] - MISO [pin 4] - MOSI [pin 5] - ROSC [pin 20] - SCLK [pin 6] - SP- [pin 13] - Sp+ [pin 15] - VCCA [pin 21] - VCCD [pin 1] - VCCP [pin 14] - VSSA [pin 8] - VSSD [pin 28] - VSSP1 [pin 16] - VSSP2 [pin 12] *The full schematic, PCB layout, bill of materials, and interactive design are available at [https://www.flux.ai/newyeork76/isd1740-voice-recorder~fe](https://www.flux.ai/newyeork76/isd1740-voice-recorder~fe).* --- *Generated from [https://www.flux.ai/newyeork76/isd1740-voice-recorder~fe](https://www.flux.ai/newyeork76/isd1740-voice-recorder~fe)*