GB2324192A

GB2324192A - A fast assemble 555 timer kit

Info

Publication number: GB2324192A
Application number: GB9707456A
Authority: GB
Inventors: Maurice Martin Lynch
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-04-12
Filing date: 1997-04-12
Publication date: 1998-10-14
Also published as: GB9707456D0

Abstract

A fast assemble 555 timer kit is a manufactured PCB to allow the easy construction of various timing circuits. Both are insulated on the underside and screen printed on top so as to allow the user easy and error free construction of simple resistor and capacitor circuits using discrete components. This is achieved by the use of three spring loaded mounting blocks across which various components are placed. The use of the spring loaded terminal block allows for simple yet effective circuit construction which bears much similarity and format to those experienced in electronic and science books. The PCB has the added advantage of being able to interface to a standard computer port thus allowing graphical illustration of what is happening on the board.

Description

Fast assemble 555 timer kit This invention relates to an dectronic teaching resource.

According to the present invention there is provided a manufactured PCB' which allows the user to model and test many basic timing electronic circuits by way of easy construction using a series of three 2-way spring loaded terminal blocks (fig 2) (A1,A2,A3) placed at right angles to the board. This board has the facility of being able to interface to a standard port of a computer and illustrating graphically the operation of the board on a computer screen. This graphical communication has many advantages, class teaching of a capacitor charging being an obvious example, whereby the charge versus time can be easily demonstrated and explained.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 - demonstrates the underside of the 555 board (track side) Figure 2 - demonstrates the upperside of the computer board (component) The top side of the 555 timer board and the track layout are shown in figure 2.

Referring to figure 2, the board consists of three parallel 2way spring loaded terminal blocks (A1,A2,A3), mounted on the board between which various sizes of resistors and capacitors can be placed.

The right-hand edge having two 4mm terminal connections (figure2) H+K allowing easy connection to a standard power supply. A voltage regulator G is place on the underside of the PCB and is used to reduce the voltage to a suitable 5 volt supply. An LED (C) indicates that the board has in fact been powered. A battery can also be used to provide power if necessary. This negates the need for a power supply if one is unavailable. The LED is protected by resistor (D).

The mid connection block (A2) is connected to pin 2 Of the LTC 1298 ADC. This will therefore measure the voltage as it increases over the capacitor.

A diode (L) is placed on the underside of the board on the ground line so as to avoid the possibility of the of any circuit damage if the polarity is reversed to the terminals +K).

The computer interface board (figure 2 ) is used to demonstrate the teaching principles and it can be easily linked to a computer via a 25 pin D-connecter . In this instance the communication is made serially via the printer port from the 25 pin 90 degree Oplug (figure 2) although it is obvious that the same effect could easily be achieved using the serial port It is important that the port be protected and to this end an opto isolated switch (figure2 - Q) has been added. This will ensure that no cuurent can be drawn from any of the printer port lines until after the board has been powered form an external source. It is important to add this protection as say a bulb or other device connected between the terminal blocks Al, A2 and A3 could draw significantly more current than the printer line would be capable of supplying. On powering the board from a suitable supply the optically isolated switch is triggered and the ground and appropriate connections are made, One line of the printer port is used to produce clock pulses using appropriately written software. A second output line is used to output data to the serially driven LTC 1298.

Another line (input) is used to receive information serially from the LTC 1298. The LTC 1298 is an ADC 12 bit converter.

The mid spring loaded block (A2) is connected to pin 2 of the LTC 1298. There are two analogue channels available and in this instance pin 3 is used to show the value of the voltage over the open switch. When the IC is being addressed the chip select (pin 1) is taken low via the printer line 4. Readings can proceed to be taken. The printer port is kept isolated from the power supply of the circuit and to this end the IC is powered directly from the printer cable (line 6). A bypass capacitor is used to maintain a smooth voltage The power supply also acts as the reference voltage The serial clock (data 5) connection goes directly from the printer port to the LTC 1298 via the D-plug connection. The serial data out (data line 2) is linked directly to pin 5 (data in) of the LTC 1298CN8. In the case of reading information from the IC then one of the printer input lines ( e g. pin 11 - busy ) connects to pin 6 of the LTC 1298CN8.

As well as feeding into channel 0 of the LTC1298 this mid point is also fed to an analogue switch DG 303ACJ. This switch is controlled by the software (via printer line 3) and on occasion it can be used to earth this mid-point, say to discharge a capacitor.

In total seven printer port connections are used: (1) SCL serial clock (output line) (2)SDA serial data (output line - write) (pin 2) (3) SDA serial data (input line - read) -(pin 11) (4) Output to switch DG303 from to discharge capacitor (pin 3) (5) Chip select (output) (pin 4) (6) Ground (7) Power and voltage reference (output) (6)

Claims

CLAIMS (1) A fast assemble 555 timer kit comprising a manufactured PCB with three 2-way spring terminal blocks, across which various resistors and capacitors can be placed to examine their effect on timing periods.

(2) A fast assemble 555 timer kit and science kit as claimed in Claim 1 wherein the power is supplied via a 12 volt direct current supply and voltage regulator or alternatively by a 9 volt battery.

(3) A fast assemble 555 timer kit and science kit as claimed in Claim 1 wherein the circuit layout is printed on the upper side of the circuit board in order to facilitate the easy assimilation with many text book circuits.

(4) A fast assemble technology and science kit in the form of a manufactured PCB as described in Claimsl,2,and 3 and allowing the added facility that the unit is capable of being interfaced to a computer port so as to allow graphical illustration of a number of important electronic principles.

(5) A fast assemble technology and science kit substantially described herein with reference to Figures 1-2 of the accompanying drawings.