Cassette player — 5V LiPo (schematic sketch)

This is a single-supply 5V design sketch (playback only). Use a regulated 5V LiPo source (or a LiPo + boost/UBEC). It shows per-channel preamp + switchable 120/70 µs EQ, VREF rail-splitter, and a single-supply headphone driver.

Power & Protection LiPo 5V IN (J1) Reverse diode D1 (SS14) C decoupling 100uF || 100nF VCC 5V VREF / Rail-splitter TLE2426 or precision rail-splitter VREF = VCC/2 (decouple 10uF || 100nF) VREF (~2.5V) Left channel preamp (MCP6002 or similar) Head L 220Ω series U1A MCP6002 (dual op-amp) +IN 47k VREF Rf1 = 82k 1k to VREF VREF R_eq=27k || C (switchable 4.3n/2.7n) 100uF AC-coupling Volume Pot (10-50k audio) Headphone amp (TPA6132A2) Single-supply 5V, connects to volume out To HP jack Right channel preamp (same as left) Head R (mirror of left channel) Motor & Drive Motor supply: use same VCC but separate ground return Motor filter: LC (10uH + 47-100uF) + RC snubber Star GND point (near LDO / input) Test pads: VCC, VREF, AGND, L_OUT_pre, R_OUT_pre, HP_OUT, MOTOR_OUT

Quick BOM (stereo)

U1 — MCP6002 (dual op-amp, 5V rail-to-rail)
U2 — TLE2426 (rail splitter) or similar (or op-amp VREF buffer)
U3 — TPA6132A2 (headphone amp) or equivalent
D1 — SS14 Schottky (reverse polarity)
R: 47k (head load) ×2, 82k (Rf) ×2, 27k (R_eq) ×2, 1k (Rg) ×2, 220Ω series
C: 4.3nF & 2.7nF film (switchable per channel), 100uF (AC coupling), 10uF/100nF decoupling
Pot: 10–50k dual gang audio taper
Switch: DPDT for 120/70 µs selection

Notes & values

• The preamp is configured non-inverting. Rf≈82k and Rg≈1k give ~100× midband. Place EQ caps in parallel/branch of Rf to produce 120/70 µs shelves — switching the cap switches the shelf corner. Use film capacitors for EQ.

• Keep head wiring short and shielded. Tie shield to AGND at the preamp only. Keep motor wiring and ground return away from sensitive analog traces; join motor ground at the star point.

• Decoupling: 100nF at every op amp; 10uF & 100nF on VREF. 100uF at the AC coupling to headphone if needed.

If you want a full Eagle/KiCad-ready netlist & footprints or a PNG/PDF export of this schematic, tell me and I will produce it next (I can also alter op-amp choice for a higher-performance 5V design).