Revitalising a Sun Jar and the Joule Thief Revisited
Cleaning out a long-neglected cupboard recently I found a Sun Jar that I had forgotten I owned. If you have […]
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Revitalising a Sun Jar and the Joule Thief Revisited
Cleaning out a long-neglected cupboard recently I found a Sun Jar that I had forgotten I owned. If you have not come across a Sun Jar before, it is a Mason jar with a circuit inside that charges up when it is light and then lights an LED in the dark; the conceit is that during the hours of daylight […]
Continue reading »3D Printing in Schools
By Tim Brotherhood and Stuart Douglas 3D printing has been around since 1984 and until recently was called rapid prototyping (RP) but the appearance of consumer devices and increasing use for production components has prompted the name change. Before we get into the nitty-gritty of the equipment and how they can be used in the classroom, a few unusual […]
Continue reading »Seetrax XL Designer
At Finham Park School, Ranger has been the principal design software for all pcbs for over 10 years. Mainly used at GCSE level, students are introduced to it in year 7. Ranger is excellent for the full range of pcb design that we do – from the simplest ‘clunky’ single sided designs to complex double sided surface mount PCBs. This […]
Continue reading »Essential Ideas in Electronics: Voltage (Part 1)
Like many essential ideas in electronics, voltage is a slippery customer; it’s easy to think you have a grip on it only to find that, when you think a bit harder about it, you don’t after all. However all is not lost; you can do a lot of useful things in electronics without holding a fully formed theory of voltage. […]
Continue reading »Essential Ideas in Electronics: Voltage (Part 2)
In this second and final part of our look at voltage, we explore what an electric potential actually is and how a voltage (potential difference) can be created. PREFACE Part 1 of this article on voltage introduced the following key ideas: • A signal in a system is a voltage • A voltage is a difference in electric potential between […]
Continue reading »Eco nightlight
The nightlight is a popular project in schools and, depending on the circuit used, suitable for a very wide student age range. Even at key stage 2, students can learn much from a basic circuit comprising a battery, switch and LED. More sophisticated automatic PIC or RC timer controlled circuits offer the scope for programming or investigation of resistor and […]
Continue reading »ZVN4206A N-Channel MOSFET
In the MOSFET, the gate is isolated from the conducting channel by a thin insulating layer (as indicated by the symbol). This forms a capacitor which can be used as the timing capacitance. As with all capacitors, the gate capacitance also has a leakage current. For the ZVN4206A the gate capacitance is typically 300pF and the leakage current 1nA. The […]
Continue reading »Long time delays – why they are difficult to achieve with just RC networks
It is difficult to achieve timing delays of more than a few minutes with the standard 555 circuit because of the way electrolytic capacitors behave. When the capacitor plates are charged a small current passes through the dielectric – this is called the leakage current. A real capacitor behaves like a perfect capacitor in parallel with a leakage resistance. To […]
Continue reading »The Nightlight – evolution of a key stage 3 project
The When I reached secondary school at the age of 11, the very first project I made in Technology (woodwork as it was then called) was a table lamp based on a halving joint. When I arrived at my present place of work, I was amazed to find that similar projects were still being made! Fortunately such projects have since […]
Continue reading »555 timers, who needs them?
The NE555 timer first appeared in 1971. Although it is now nearly 40 years old, many exam boards still include it in their specifications. This seems rather odd in a fast developing subject such as electronics. With an ever expanding range of new technology and devices to learn about, perhaps it is now time to relegate the 555 to the […]
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