TREE

The old nut on our Hofner Colorama II was in a terrible state. It was too shallow and had a piece of card underneath it in order to raise it up. Additionally the bottom was not flat. Here it is: I have no reason to trust this nut at all, so I'm not going to use it as a template for the new one. So here I am sanding a new piece of bone down to the right thickness using a piece of coarse sandpaper set on a flat surface: Then cutting the bone to length: Here I’m checking it fits nicely into the nut slot: Before I can continue, I need to make up a new half pencil, since I appear to have misplaced my old one. So we take a normal pencil: Slice it down the middle (watch your fingers): Superglue the lead into place (optional, but I find it a good idea, since there’s nothing really holding the lead in place at this stage): Remove superglued finger from pencil (again, optional): Sand pencil flat: And then I usually put some Sellotape (Scotch tape) along the bottom of the pencil to stop from ...

The supply receives - 20 V from the rectifier/filter which is fed to the collector of the Darlington pnp pass transistor, a TIP105. The base drive to the TIP105 is supplied through resistor R5. The base of the TIP105 is driven from Vz terminal at pin 9, which is the anode of a 6.2-V zener diode that connects to the emitter of the uA723 output control transistor. Circuit diagram : 15-V 1-A Regulated Power Supply Circuit Diagram The method of providing the positive feedback required for foldback action is shown. This technique introduces positive feedback by increased current flow through resistors R1 and R2 under short-circuit conditions. This forward biases the base-emitter junction of the 2N2907 sensing transistor, which reduces base drive to the TIP105.

The supply receive from 220 /120/110 Volt AC , then lowered by the transformer . Then receives +20 Volts DC from rectifier / filter section. This applied to pin 11 and 12 of the IC uA723/LM723 , as well as to the collector of the 2N3055 series pass transistor. The output through R1 and R2, providing about 7 V with respect to ground at pin 4. The reference terminal at pin 6 is tied directly to pin 5 , the non inverting input of the error amplifier . For fine trimming the output voltage , a potentiometer can be installed between R1 and R2. A 100-pF capacitor from pin 13 to pin 4 furnishes gain compensation for the amplifier. Base drive to the 2N3055 pass transistor is furnishes by pin of the uA723. Since desired output of the supply is 1 Ampere, maximum current limit is set to 1,5 Ampere by resistor Rsc whose value is 0,422 Ohm. A 100uF electrolytic capacitor is used for ripple voltage reduction at the output. A 1 kOhm output resistor provides stability for the power supply under no - lo...