Home > Circuit BLOX > Notes for Teachers
UPDATED:.16:13 31 August 2014

NOTES FOR TEACHERS

BLOX can be used as part of:

  • Demonstrations
  • Student coursework
  • Syllabus specification

The notes below are meant as guidance for teachers and students when using BLOX. These notes may updated.

PAGE CONTENTS:

General Notes
Power Suplies
Connection
Construction
Fault Finding


GENERAL NOTES

There is a page containing operating and circuit details on each BLOK. BLOX can be used together and/or integrated into other circuits.

If used with other circuits, ensure that the circuitry and the BLOX share the same power supply. Check the BLOX voltages to ensure they are not exceeded.

BLOX can be used for quick fixes, such as a Darlington driver or IR remote control. They can also be used to develop more complex circuits. There are a range of exemplar circuits available on the BLOX page that demonstrate how BLOX can be added, combined and connected.

Circuits can be modified easily such as adding an inverter to change logic signals, or a latch to trap events from sensors.

There are some digital BLOX are being developed such as Decade Counters for sequencing and Binary Counters for more complex timing control.

Many BLOX have option settings to change range, polarity or function. You can also change these options purposefully to experiment with the operation of circuits - such as the Warbler Siren. The circuit BLOX will not be damaged.

BLOX can easily be screwed down onto the rear of boards or into the cases of projects.

POWER SUPPLIES

BLOX all work with a supply between 9 and 12 volts and most have the capability to work down to 4.5v easing battery supply. Supplies over 12 volts can be used where BLOX allow. Try not to change supply voltage while the circuit is functioning. Switch off and wait a few seconds for any supply capacitors to empty, then re-connect supply at new voltage.

BLOX are fairly robust but over voltage or power polarity reversal can cause permanent damage. There are components and PIC chips available for all BLOX should any damage occur.

When using Darlington drivers to power devices with a different power supply to the circuitry, ensure that the 0v connection on both supplies is connected (the circutry supply and the device load supply).

CONNECTION

BLOX are connected using solid core wire into PCB terminal blocks. These terminal blocks have a metal lug that sits below the screw to protect the wire from twisting action. When used for the first few times, the lug can become stuck down and difficult for the insertion force of the wire to lift. If this happens, open the screw almost fully, and gently lever up the lugs with a small screwdriver or scriber. This should free up after some use.

It is recommended to create a stock of solid core connecting wires, cut to one or two set lengths. This makes connection very easy. When inserting wires, connect all wires to one block first keeping them as straight and parallel as possible. Then open the screws on the next block terminal and insert all wires at once.

Precision screwdrivers (fairly large) are good for terminal connections. The swivel top can be supported in the palm of the hand while fingers spin the screw.

CONSTRUCTION

Assembly instructions are available in the BLOX index and on the individual BLOX pages. They are in pdf format and offer a guide for students to follow. Please review any new additions that appear on the site.

Try not to handle the pins of the IC's too much as the CMOS ones are static sensitive. They have diode protection to prevent low static discharge damaging the inputs. Large discharges generated by static build up from shoes on carpets for example, can destroy IC's instantly.

The IR detector is static sensitive and should be handled with snipe-nosed pliers and/or ensure the user is grounded. The soldering iron should also be grounded when soldering.

A 15 or 18 Watt soldering iron is ideal for soldering components. Use a stand with a wet sponge and a good quality solder.

PCB holes are different sizes depending on the component. Sometimes they can be quite a snug fit. Take care not to bend the component wire as this will make insertion into the holes difficult.

The assembly instructions have the order of soldering components in height order. This is to ease access to component holes only.

Check for any solder bridges, particularly with IC's and components close together.

FAULT FINDING

If the BLOX are constructed as kits, then a common problem is the incorrect orientation or placement of components. This can have fatal consequences for some components, such as diodes.

IC's can tolerate about 5-10 seconds of reverse polarity before damage occurs. A test done with care, is to check for any heat coming from IC's, this is a good sign of connection or supply problems.

Ensure the power supply has enough current capability to drive your circuit. Loads such as motors and bulbs can cause weak batteries or low current power supplies to dip their voltage causing chattering and unexpected circuit performance.

Many BLOX have option settings, such as range selection, polarity or function mode. Ensure you have selected the correct options for each block.

If you have a problem with a circuit using BLOX, email us a picture from above and include the supply you are using and we will try and help you.
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