One of the intended applications of the CNC router is to cut openings in Jiffy boxes for things like LCD displays, tactile button switches, connectors etc.
After a lot of testing, it came time to try it on some target work.
Above is a scrap Jiffy box and the milling job is to cut holes for three pushbuttons (tactile momentary switches on a veroboard base with 10mm caps) and the holes for M3 screws and pillars. Continue reading CNC6040 router project – test cut of a Jiffy box
A known issue with the common CNC6040 router and similar devices is very poor calibration / linearity of the spindle motor response to gcode Sx commands.
Above is the system block diagram. The grbl_ESP32 gcode interpeter processes a gcode S (speed) command, converting it to a variable duty cycle PWM waveform on parallel port pin 1. Continue reading CNC6040 router project – spindle speed linearisation – using new grbl_ESP32 feature
A known issue with the common CNC6040 router and similar devices is very poor calibration / linearity of the spindle motor response to gcode Sx commands.
Above is the system block diagram. The grbl_ESP32 gcode interpeter processes a gcode S (speed) command, converting it to a variable duty cycle PWM waveform on parallel port pin 1. Continue reading CNC6040 router project – spindle speed linearisation
OpenLog for TinyTrak described a data logger for APRS NMEA data.
This article shows an innovative inline adapter for adding an Openlog to an existing APRS installation where the GPS is powered with 5V via the DE9 connector.
Above, the adapter comprises a DE9 male and DE9 female connector cabled together as a through connection, and the Openlog is wired into one of the backshells, wrapped in heat shrink tube, and velcro’d to the backshell. Continue reading OpenLog for TinyTrak – inline DE9 adapter
Designing with ferrite binocular cores can be frustrating as there are different formats in which data is provided, and data for different mixes on the same dimensioned cores appear inconsistent.
There are several source of the Al parameter for some common cores, often from resellers rather than manufacturers. Continue reading Designing with binocular ferrite cores – published Al values
Designing with ferrite binocular cores can be frustrating as there are different formats in which data is provided, and data for different mixes on the same dimensioned cores appear inconsistent.
This article documents calculated geometry Σ(A/l) derived for a number of Fair-rite cores from their specified Al (at µi). Continue reading Designing with binocular ferrite cores – Σ(A/l)
The STC15Fx chips use a simple TTL/CMOS async programming interface that is suited to the common USB-RS232(TTL) adapters. This article describes a low cost programmer that also allows the programming application to Vcc (so initiating the boot loader automatically).
Above is the programmer ($2.50 on eBay) and a small adapter that plugs into the top row of the 2×5 header on the programmer.
DIP-28 are located carefully so that the pins 10-18 are in the socket, the same connections are used for both chip sizes for STC15F104E and STC15F204E. Continue reading Basic programming jig for STC15F104E and STC15F204E chips #3
STC produce the U8W & U8 programmers for a range of their chips.
The thing has a JST 7way XH socket provided for an ISP connection to a target board. It is accessed through a cutout in the acrylic housing, but the cutout is no bigger than the shoulder on an XH plug and one cannot get tools in beside it to pry the plug out without pulling on the wires.
The good thing is that there is an inexpensive “XH plug saver” sold to the RC market, it provides a means of getting a convenient grip on the plug without pulling on the wires.
First step is to mill out the case opening to accommodate the XH plug saver.
Next, add the XH plug saver to the XH plug, and it all works. Continue reading XH plug savers on the STC U8W & U8 programmer
A recent purchase of an inexpensive ($6) speaker polarity tester prompted a need for a stand alone driver for speakers.
Above, the tester has a microphone that senses the polarity of the pressure wave and indicates with one of two LEDs.
The tester comes with a CD containing a file that can be used to provide the test signal on a complete system with CD player, but there is a need for a stand alone driver for testing bare speakers or speaker units.
Speaker tick generator (for polarity testing) described a stand alone test pulse generator based on re-purposing a brushless DC motor controller (ESC, used for RC models).
This article describes a simple tick generator using a inexpensive 8051 type MCU (STC15F104E) and a H-bridge IC (TC427).
Above, the prototype was build on a small piece of Veroboard. DC input of 6-15V is applied to the 2.1×5.5mm DC jack, and speaker output is on the screw terminals (nearest to DC jack is -ve). Continue reading Speaker tick generator #2 (for polarity testing)
Fox Flasher MkII and several follow on articles described an animal deterrent based on a Chinese 8051 architecture microcontroller, the STC15F104E.
This is an update after several years operation outside, and some in service modifications to improve performance.
Above is the original basic schematic.
Above is the revised schematic. One only high current LED driver is shown, use as many as needed. The battery charger / protection module is based on TP4056 and DW01 chips and modules sell on eBay for $1 or so. Continue reading Fox flasher MkII update 7/2019