This is a simple square wave oscillator using a 4011 NAND chip, you could of course use the TTL equivalent as well. Adjusting the resistor values will adjust the mark/space ratio of the square wave output Schematic Parts List QTY PART-REFS VALUE --- --------- ----- Resistors --------- 1 R1 100k 1 R2 22k Capacitors ---------- 1 C1 10nF Integrated Circuits ------------------- 1 U1 4011 Diodes ------ 2 D1,D2 1N4148
Description A very simple LED flasher circuit using an LM3909, these were great because you could connect a 1.5v battery up to them. They are hard to come by nowadays. Schematic Parts List QTY PART-REFS VALUE --- --------- ----- Capacitors ---------- 1 C1 220uF Integrated Circuits ------------------- 1 U1 LM3909 Diodes ------ 1 D1 LED Miscellaneous ------------- 1 BAT1 1.5V Links
Description This is an adaptation of the PSU that uses a 7805 and can supply higher current. You need to use an appropriate heatsink for the 2N3055 transistor, you could also use a TIP3055, using a 2N3055 you can get roughly 10 amps. This transistor in the circuit below simply allows the current to flow through the collector emitter leads. The output voltage is maintained by the 7805 regulator but the current flows through the "pass transistor". You can actually use a 78L05 to supply the 5v output as the transistor supplies…
Description As you may recall the LM317 regulator is adjustable from 1.25 to about 35v. By adding 2 diodes you can drop the voltage slightly, about 0.6v of a voltage drop across each diode, so in the schematic below you can get close to 0v Schematic Parts List QTY PART-REFS VALUE --- --------- ----- Resistors --------- 1 R1 220R Capacitors ---------- 2 C1,C3 100nF 1 C2 100uF 1 C4 10uF Integrated Circuits ------------------- 1 U1 LM317T Diodes ------ 2 D1,D2 1N4004 Miscellaneous ------------- 1 RV1 5k
Description You can, with a little modification use a 7805 regulator to generate a variable voltage output, in the example below the output can be 5v to 30v. At higher output voltages you should fit a suitable heatsink to the 7805. Schematic Parts List QTY PART-REFS VALUE --- --------- ----- Resistors --------- 1 R1 220R Capacitors ---------- 2 C1,C3 100nF 1 C2 100uF 1 C4 10uF Integrated Circuits ------------------- 1 U1 78L05 Miscellaneous ------------- 1 RV1 5k
Description This is a basic 9v to 5v PSU using a 7805 regulator, this was a common circuit to build for building a low cost 5v stabilised DC supply using a 9v PP3 battery as an input source Schematic Parts List QTY PART-REFS VALUE CODE --- --------- ----- ---- Capacitors ---------- 2 C1,C2 1nF 2 C3,C4 1uF Integrated Circuits ------------------- 1 U1 7805
Description A simple book light Schematic Bill of materials QTY PART-REFS VALUE CODE --- --------- ----- ---- Resistors --------- 1 R1 150K 1 R2 120R 2 R3,R4 100K Capacitors ---------- 1 C1 10nF 1 C2 220uF Transistors ----------- 1 Q1 NPN 1 Q2 PNP Diodes ------ 1 D1 3V Bulb Miscellaneous ------------- 1 BAT1 3V 1 SW1 Push Button switch
This is a basic DC power supply using the 78XX voltage regulator. Schematic Parts List QTY PART-REFS VALUE --- --------- ----- Capacitors ---------- 1 C1 1000uF 1 C2 100uF Integrated Circuits ------------------- 1 U1 78XX Miscellaneous ------------- 1 BR1 BRIDGE RECTIFIER 1 FU1 3A Fuse 1 TR1 TRAN-2P2S - 115v primary / 24 v secondary
This is the most basic example of using a LM317 voltage regulator. The variable resistor (R1) and R2 are used to select the output voltage. The Lm317 is capable of delivering up to 1A of output current depending on the type you have.The input voltage can be up to 40V and output voltage can be adjusted from 1.2V to 37V. In our example we recommend 28v max. A heat sink must be fitted to the LM317 where the output current exceeds 250 milliamps. Bill of materials QTY PART-REFS VALUE --- --------- ----- Resistors --------- 1 R1…
Description A simple LED flasher using a 555 timer Schematic Bill of materials Resistors --------- 2 R1,R3 1k 1 R2 470k Capacitors ---------- 1 C1 1uf Integrated Circuits ------------------- 1 U1 555 Diodes ------ 1 D1 DIODE-LED