Speaker tick generator #2 (for polarity testing)

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 update 7/2019

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.

ff201Above 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

Basic programming jig for STC15F104E and STC15F204E chips

The STC15Fx chips use a simple TTL/CMOS async programming interface that is suited to the common USB-RS232(TTL) adapters, some of which are less than A$2 on eBay (CH341 chip).

Above, the completed adapter. 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

Trying to make sense of the STC U8W chip programmer

STC is a Chinese maker of microcontroller chips, mostly 8051 architecture. The whole environment is characterised by a lack of English language information, or unreliable information.

The U8W is a programmer for some of their chips, and works in concert with their ISP programming software (Windows).

Above is the U8W. It was supplied without any documentation by an Aliexpress seller. Requests from the seller and from STC have not yielded any information. Continue reading Trying to make sense of the STC U8W chip programmer

Fox flasher MkII – update 07/2019

Fox flasher MkII described a LED driver for an animal deterrent using a Chinese 8051 architecture microcontroller, the STC15F104E.

ff201a

Above, the schematic. A very simple circuit with just a handful of electronic components (one capacitor, two resistors, one LDR, one Polyswitch, 4 x LEDs and the MCU). Note the capacitor in shunt with the LDR, it is to reduce noise and to provide a level of RFI protection. Continue reading Fox flasher MkII – update 07/2019

The private and public scope of coaxial cable

Let’s start by reviewing the concept of inductance.

Inductance

Inductance of a conductor is the property that a change in current in a conductor causes a electro motive force (emf or voltage) to be induced in a conductor.

We can speak of self inductance where the voltage is induced in the same conductor as the changing current, or mutual inductance where the changing current in one conductor induces a voltage in another conductor. Continue reading The private and public scope of coaxial cable

Fox flasher MkII – high power 2 LED solar powered beacon – update 6/2019

Fox flasher MkII – high power 2 LED solar powered beacon described a LED driver for an animal deterrent using a Chinese 8051 architecture microcontroller, the STC15F104E.

FF100This article documents its failure  in June 2019 after five years service.  Continue reading Fox flasher MkII – high power 2 LED solar powered beacon – update 6/2019

Fox flasher MkII – high power 2 LED solar powered beacon – update 6/2018

Fox flasher MkII – high power 2 LED solar powered beacon described a LED driver for an animal deterrent using a Chinese 8051 architecture microcontroller, the STC15F104E.

FF100This article documents its failure  in June 2018 after three years service.

With the passage of time, the PV array surface has degraded until solar collection was insufficient to maintain the battery over several heavily overcast Winter days.

Above, a close up of the PV array surface. The pic is of about 8mm width, and one can barely see the silicon stripes which are about 2mm wide. Continue reading Fox flasher MkII – high power 2 LED solar powered beacon – update 6/2018