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.

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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

Derating rectifier diode current

The ratings for rectifier diode currents are often expressed in terms of a steady (ie DC) current, yet when used as a power rectifier with capacitor input filters, the current is very different.

Above is capture of the rectifier input current for a lab power supply set to 1A load current, the scale factor for the current probe is 1V/A. Continue reading Derating rectifier diode current

Hitachi DB3DL2 UC3SFL repair

The UC3SFL charger for my Hitachi DB3DL2 screwdriver departed this world after just 8 years with a bang, several parts around the main switching transistor deposited as soot inside the cover.

Above is a view of the underside of the charger board, it is very complex, lots of parts, and there are lots of parts on the topside. Ouch, this is going to be expensive.

Yes, it is the replacement power supply is more than half the price of complete tool with two batteries (~$200)… so that is not on.

Modification / fix

The screwdriver’s LED control board has already failed (probably a low grade Chinese electrolytic capacitor) and had to be removed as it would switch on spontaneously and flatten the battery. The hole left vacant by the removed push button provides a convenient exit for a charger cable. Continue reading Hitachi DB3DL2 UC3SFL repair

Capacity test of aftermarket NB-6L batteries #2

I purchased a further two replacement batteries type NB-6L for a Canon camera from yet another supplier.

Above, the batteries are labelled 1000mAh. They appear to be well made externally, and fit charger and camera fine.

Note that these have different labeling to that shown in the eBay listing. It is naive to expect that the supplied item matches either pics or description, bait and switch is a standard Chinese technique. Continue reading Capacity test of aftermarket NB-6L batteries #2

Capacity test of aftermarket NB-6L batteries

I purchased two replacement batteries type NB-6L for a Canon camera.

Above, the batteries are labelled 1050mAh. They appear to be well made externally, and fit charger and camera fine.

Note that these have different labeling to that shown in the eBay listing. It is naive to expect that the supplied item matches either pics or description, bait and switch is a standard Chinese technique. Continue reading Capacity test of aftermarket NB-6L batteries

Geometry factors for some common Fair-rite binocular ferrite cores

Designing with some common Fair-rite binocular ferrite cores can be frustrating because different parameters are published for different material types, and some are controlled for different parameters.

An approach is to derive the key geometry parameter from the published impedance curves and published material complex permeability curves.

For example, the above curves for a 2843002402 (also common known as a BN43-2402) were digitised and iteratively Calculate ferrite cored inductor (from Al) used for find the value of Al that gives the observed value for Z at 10MHz on the chart above. Continue reading Geometry factors for some common Fair-rite binocular ferrite cores