inferno Posted September 11, 2004 Report Share Posted September 11, 2004 ei! help me with circuit.. i want to change the semiconductors...will you please suggest a substitute for this.. tnx!!Resistors (all 1/4W 5% carbon film)R1,R9 1k (brown, black, red, gold)R2,R10,R11 470R (yellow, purple, brown, gold)R3,R13 10k (brown, black, orange, gold)R4 1M (brown, black, green, gold)R5 2k2 (red, red, red, gold)R6,R8,R15 220R (red, red, brown, gold)R7 10R (brown, black, black, gold)R12 560R (green, blue, brown, gold)R14 100R (brown, black, brown, gold)R16-R23 330R (orange, orange, brown, gold)Capacitors (electrolytics 2.5mm spacing, others 5mm)C1,C4,C6 100u electrolytic 16VC2,C5,C7 220u electrolytic 16VC3 100n miniature polyesterC8,C11 100n ceramicC9,C10 22p ceramicSemiconductorsTR1,TR3,TR4 BC549B npn transistor (or BC547B, 48C etc.)TR2 BF244A or B N-channel JFETTR5 ZTX313 npn switching transistorD1-D3 1N4148 silicon diodeD4 BAT42 Schottky diodeREG1 LP2950 5V regulatorIC1 18-pin DIL socket + PIC16C54 HS/P microcontrollerDISPLAY1,2 0.56" dual 7-segment LED display, common cathodeMiscellaneousX1 20MHz crystal, HC-49/U caseS1 miniature pcb vertical slide switch, SPDTINPUT BCN pcb socketBATTERY PP3 battery snap4 x rubber feet...... below is the schematic.....frequency_counter.pdf Quote Link to comment Share on other sites More sharing options...
audioguru Posted September 11, 2004 Report Share Posted September 11, 2004 Hi Inferno,Why do you want to change the semiconductors?It looks like a very nice project that is designed to use those ones.If you can't get the parts, or don't want to program its microcontroller, then just buy the kit.I'll bet that it eats batteries because of its LED display.At first I thought that its voltage regulator will also eat batteries, because it is still powered even though the rest of the project is turned off. But then I realised that it is a special low-power regulator, and that the microcontroller needs a very quick power-up to properly reset. Quote Link to comment Share on other sites More sharing options...
absolution Posted September 23, 2004 Report Share Posted September 23, 2004 2n3904s are nice but somewhat expensive compared to various others. just get datasheets most of the replacements you can find at your local radioshack. Quote Link to comment Share on other sites More sharing options...
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