The basis sequence of 6 positions is thus repeated 4 times. Practically I have found 24 stable positions. Read more »Ī Hard disk drive motor has more coils than this simple triphased motor. On the left side picture you can see half. A dark spot is painted on the disk to be detected easily by the sensor. A hole is drilled in the disk enclosure for that. As we will engrave the platter with hours marks, we need to have a way to know "where is noon".Ī RPR220 phototransistor is soldered on the PCB (details will come) and its led focusses IR beam on the bottom platter of the disk. When the disk rotates you don't know what is its position. And we will see that the rest of the clock is much more digital! When I said that this clock would be "analog and digital" I wasn't lying at all. Our HDD heads arm is almost a galvanometer but it must be equiped with a litlle torsion spring to convert it into a DIY moving-coil galvanometer. The hand points at a scale indicating the electric current The coil twists, pushing against the spring, and moves the pointer. This field acts against the permanent magnet. When a direct current (DC) flows through the coil, the coil generates a magnetic field. A tiny torsion spring pulls the coil and pointer to the zero position. The coil is attached to a thin pointer that traverses a calibrated scale. The D'Arsonval/Weston galvanometer used today is constructed with a small pivoting coil of wire in the field of a permanent magnet. It is an analog electromechanical transducer that produces a rotary deflection of some type of pointer in response to electric current flowing through its coil in a magnetic field.
Wikipedia tells us that a moving-coil galvanometer is a type of ammeter: an instrument for detecting and measuring electric current. Time should be kept in case of a power failure.
the disk should be powered by any 5V coming either from a USB charger or directly from a PC USB host.the device should be automatic on startup.the rotating disk should indicate the hours.the head arm should indicate the minutes.
This project was published on my Website ten years ago, but I will now publish the whole design, the source code, everything in open source and open hardware.Īnd, If I am not too lazy, I will as well try to port it on an ESP32 MCU and design an android App to get rid of the PC App which is a bit outdated today! Hall ** Email: **/ #ifndef F_CPU #define F_CPU 16000000UL // 16 MHz #endif #include #include #include #include #include #include "Chronodot.h" // arduino redefines int, which bugs out stdio.Now let's see how all this works and how you can do your own "HDD clock". You should have received a copy of the GNU General Public License along with this program if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. See the GNU General Public License for more details. Hall This program is free software you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2 This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
** hdpov.c - Arduino driver for Hard Drive POV Copyright (C) 2008 Giles F.