Mutchus

This white-LED driver circuit is ideal for use in a garden light. It automatically turns the LED on at night and runs from a single 1.2V nicad cell which is recharged by a solar cell during the day. The prototype used the existing casing and solar cell from an old garden light but you could also use a solar cell from a solar education kit. Diode D1 allows the solar cell to charge the battery during the day and prevents it from discharging back into the solar cell at night. Transistor Q1 controls the LED driver circuit. This transistor is normally on during the day (ie, when there is output from the solar cell) and so Q2 and the LED are off. At night time, Q1 is off and this allows a simple blocking oscillator circuit based on T1, R2 and Q2 to operate. This circuit in turn drives LED1 via a 1W resistor which limits the peak current into the LED. T1 is wound bifilar, with the two windings configured to produce a center-tapped winding. Winding AB is the main primary winding and winding BC...

BRIGHT FLASH FROM FLAT BATTERY This circuit can flash a white LED, on a provide from 2v to 6v and turn out a really bright flash. The circuit takes regarding 2mA and recent cells are often used. the 2 100u electros in parallel produce a much better flash when the availability is 6v. 3v WHITE LED FLASHER This will flash a white LED, on 3v provide and turn out a really bright flash. The circuit produces a voltage on top of 5v if the LED isn't in circuit however the LED limits the voltage to its characteristic voltage of three.2v to 3.6v.   The circuit takes regarding 2mA an is really a voltage-doubler (voltage incrementer) arrangement. Note the 10k charges the 100u. It doesn't illuminate the LED because the 100u is charging and also the voltage across it's invariably less than 3v. When the 2 transistors conduct, the collector of the BC557 rises to rail voltage and pulls the 100u HIGH. The negative of the 100u effectively sits just under the positive rail and also the positive...

Tiny white LEDs are capable of delivering ample white light without the fragility problems and costs associated with fluorescent backlights. They do pose a problem however in that their forward voltage can be as high as 4 V, precluding them being from powered directly from a single Li-Ion cell. Applications requiring more white LEDs or higher efficiency can use an LT1615 boost converter to drive a series connected array of LEDs. The high efficiency circuit (about 80%) shown here can provide a constant-current drive for up to eight LEDs. Driving eight white LEDs in series requires at least 29 V at the output and this is possible thanks to the internal 36-V, 350-mA switch in the LT1615. The constant-current design of the circuit guarantees a steady current through all LEDs, regardless of the forward voltage differences between them. Although this circuit was designed to operate from a single Li-Ion battery (2.5V to 4.5V), the LT1615 is also capable of operating from inputs as low as 1...

Valve and Transistor - Grundig Black and White TV - 1962 model - Grundic Eleganz 2300SE CIRCUIT DIAGRAM   I know; nobody will have this model set (working) now.  Yet, publish this post to compare its assembly and schematic with modern Televisions.  Even though it is B/W TV, weigh about 45 kilograms.