Electronics, hardware

EQMOD adapter for telescopes. Version 2

This is a short note about the upgraded version of my old EQMOD adapter for telescopes.
Technically, this device it’s a USB – UART adapter with galvanic isolation. That’s why it might be used not only for telescope control.
It’s a third revision of the board.

From users’ reports, I found that sometimes it’s easy to kill the adapter with a higher voltage supply from the telescope mount side.
The original adapter used AMS1117-5 for the isolated side. This voltage regulator can handle up to 15 V of input voltage.
Higher voltage kills the regulator and ADUM1201 isolator.
I decided to use the L78L05 voltage regulator. The new regulator can handle up to 30 V input voltage at 100 mA current.

Also, the original adapter lacks any indication. Many people asked, so I decided to add Power and TX/RX LEDs.

Schematic of the new adapter:

Click on the image for full resolution.

The board layout was optimized for better isolation and component placements. There are no bulky capacitors.
L78L05 voltage regulator cooling by a massive copper polygon.

Finished board (New fancy color!):

I covered the board with three layers of special varnish for additional protection.

One of the readers asked for a DIY kit, so I prepared one 🙂

BOM:

PartValuePackageDescription
C110 nFC0805CAPACITOR
C2100 nFC0805CAPACITOR
C30.1 μC0805CAPACITOR
C40.33 μFC0805CAPACITOR
C5100 nFC0805CAPACITOR
D14V7SMB-DIODEZener Diode
D25V1SMB-DIODEZener Diode
IC1FT232RLSSOP28DBUSB UART interface
IC2ADUM1201SO8UART isolator
JP1USB-BUSB-B-PTHUSB Connectors
L1FERRITE0805Ferrite bead
PWRCHIPLED_0603LED
RXCHIPLED_0603LED
TXCHIPLED_0603LED
R1200R0805RESISTOR
R2200R0805RESISTOR
R310R0603RESISTOR
R410R0603RESISTOR
R5270R0603RESISTOR
R6270R0603RESISTOR
R7270R0603RESISTOR
U$1RJ45-8PTHRJ45-8 RJ45 Jack
U1L78L05ABD13TRSOIC127P600X175-8NPositive voltage regulators

Eqmod2 gerber files.

Thanks for reading!

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