Disclaimer: Version 1 does not work! Version 2 is the ‘good’ one.
for record sessions over 1 minute the AMS1117 regulator gets to hot and shuts off.
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The Problem
If you want to record an MD with the Sony MZ-N707 you have to plug in the mini usb cable and have an AA-battery inside of it. I reworked the player, so it takes the power from the USB and converts it to 1.5V to mimic a fully chared battery.
I decided on 1.5V instead of 1.2V (more headrum if the voltage spikes) because the motor in the player can draw 220mAh for a few seconds even @1.5V. Do reduce the strain on the thin wires I used I opted for the upper end of the Voltage-curve.
Version 1: off the shelf Voltage regulator (not good)
Here is what I used:
- Sony MZ-N707 Player
- 1.5V regulator (on board from aliextress)
- Capacitor 16V 220μF Cap (for more stable rail while surgedraw)
As mentioned in the disclaimer this did not work very good. Thats the reason for version 2!
Version 2: DC-DC buck regulator
BOM:
- U1: IC ACT4088
- C1: Capacitor 22nF
- C2: Capacitor 10uF
- C3: Capacitor 22uF
- D1: Diode (I used SS12)
- L1: Inductor 4.7uH
- R1: Resistor 51kΩ
- R2: Resistor 75kΩ
After soldering and testing it turns out that the contact via copper tape is not good enough. So I had to add wires back to the device. But with this done it wored flawlessly.
The Gerber in this article is a bit newer than the one I soldered, but its just bigger traces for the second DC site for better voltage stability on surgespikes. Technically they are the same.
With the new board in place I recorded a full MD without any drops.