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It has been a while since I did anything really crazy in DIY and had it work out far above my expectations. Such is the case for the Mini Blocks. I had a lot of extra parts lying around (really a huge amount of them) and tried to figure out what I could build. Two small chassis about 5 inches by 9 inches by 2 inches (12.5 X 22.5 X 5 cm) were just begging for a project. They are just the right size for lots of things. I first thought of a pair of SET amps. But since I didn’t have any suitable single ended output transformers I nixed that idea. A preamp perhaps could be built on one of the chassis. Since I have many preamplifiers now that didn’t really get the nod either. A pair of small push-pull amplifiers was next on the list. Maybe, but I have so many amps now that it doesn’t make sense either. Since this hobby doesn’t always have to make sense, that is what I built. [ ]

Automatic switch-on when it gets dark, 6V or 3V battery operation This design was primarily intended to allow automatic switch-on of push-bike lights when it gets dark. Obviously, it can be used for any other purpose involving one or more lamps to be switched on and off depending of light intensity. Power can be supplied by any type of battery suitable to be fitted in your bike and having a voltage in the 3 to 6 Volts range. The Photo resistor R1 should be fitted into the box containing the complete circuit, but a hole should be made in a convenient side of the box to allow the light hitting the sensor. Trim R2 until the desired switching threshold is reached. The setup will require some experimenting, but it should not be difficult. Circuit diagram: Push-Bike Light Circuit Diagram Parts: R1_____________Photo resistor (any type) R2______________22K 1/2W Trimmer Cermet or Carbon type R3_______________1K 1/4W Resistor R4_______________2K7 1/4W Resistor R5_____________330R 1/4W Resistor (...

Tube Power Amplifier 35W Push Pull is made using a tube and eventually compiled configuration push-pull amplifier. Tube Power Amplifier 35W Push Pull tube til it using EL-34 as the amplifier end. In the power amplifier that is made with a tube at a glance looks simple because the use of active components that are not complex. It should be noted that the use of tubes in Tube Power Amplifier 35W Push Pull require a high voltage supply, therefore in the process of making and finishing must be careful of high voltage and radiation. Detailed series of Tube Power Amplifier 35W Push Pull can be seen in the following figure. Tube Power Amplifier Series 35W Push Pull Sign Components Tube Power Amplifier 35W Push Pull R1 = 470K 0.5 W R2-5 = 2K2 0.5W R3 = 150K 0.5W R4 = 220K 0.5W R6-10 = 56K 0.5W R7 = 3.9K 0.5W R8 = 220R 0.5W R9 = 1M 0.5W R11 = 39K 1W R12-23 = 180K 0.5W R13-21 = 820K 0.5W R14-22 = 5K6 0.5W R15-20 = 680K 0.5W R16-19 = 100K 0.5W R17-18 = 3K3 1W R24 = 470R 2W TR1-2 = 470R 1W Variabl...

This Push-Pull Square wave DC-to-AC Inverter uses inverter gates for the oscillator part, then use one of the gate to invert the produced square wave signal. With push pull operation, the primary coil of the transformer is driven with alternate direction, with the help of H bridge of power transistors (MOSFET) 2SJ471 and 2SK2956.Using the transformer shown in the schematic diagram, this inverter circuit produce 110VAC from 12VDC input, but you can easily modify this circuit to produce 220VAC by replacing the transformer with 220V type (12V-220V) of the same amperage (10A).   Push-Pull Square wave DC-to-AC Inverter

Push button is a piece of metal contact with two metal pieces. They provide a temporary path, so that charge can flow. They have a inbuilt spring which makes it return to the normal position when released. There are Two types of Push buttons basically: Push Button Normally Open (PBNO) Push Button Normally Closed (PBNC)   Figure 1: Basic Push Button