PROJECTIN

LOGSIGN

Submitted to: Mr. Joel Fontanos

Submitted by: Group 1

Vanessa Fernandez Joshua Bagang

Scarlet Calpo Niel Bumanlag

Eric Baladad

Grading sheetVanessa Fernandez

Scarlet Calpo

Eric Baladad

Joshua Bagang

Niel Bumanlag

Jasper

II. PURPOSE

AFTER buying a small low voltage drill for working on printed circuit boards, it was noticed that the drill motor would stall if the input voltage was less than 15V. This voltage resulted in a higher power but also a higher drill speed which increased the heat and wear on the drill bit, rapidly making it blunt. The circuit diagram shown in Fig.2 uses pulse control to decrease the drill speed while maintaining the output power.

C1a is one half of a 556 timer and is set in astable mode to provide a base frequency of approximately 150Hz. This is fed into IC1b which triggers the monostable, set by Speed potentiometer VR1 to have a period of between 0·1ms to 10ms. The duration of the monostable determines the period that the drill motor has the full 15V potential across it, and hence the speed of the drill which is lowest when the time period is 0·1ms. The output of IC1b is connected to the base of transistor TRl which is a high current (3A) power transistor that controls the load. It is protected from inductive voltage spikes by diode D1. The circuit proved to be very effective and can be powered from an existing 12V to 15V d.c. drill power supply unit.

final output

analysis and design

writing manual

convert file

data gathering

planning

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Project Schedule

Column1

I. iNTRODUCTION

iii. iLLUSTRATION