Kit Review

The Quasar Electronics 12-Channel InfraRed Relay Board ..reviewed by Tony Dixon G4CJC

This unit enables 12 relays (in two banks of 8 and 4) to be switched on and off individually and independently or off simultaneously. As such it will find many applications in a constructor's domain.

The kit from Quasar Electronics, came packed in the familiar padded Jiffy bag.
Inside was a sturdy transparent plastic box enabling me to see the various components, pcb and the remote control hand unit before opening it.

The components were further sealed into 4 cellophane compartments, which enabled easy checking without opening the cellophane. All components were present and correct.

This part of any construction is important. It's bad enough if a component is missing during construction but if you find one (or more) left at the end you may waste a lot of time trying to find where it should have been put! The instructions are very succinct and more than sufficient. Although the font size is small, the print is clear and the circuit diagram sharp.
(Click here to view the circuit diagram)

The printed circuit board is of excellent quality, plated through, with high definition coated tracks and holes and spacings that exactly match the components. All of the component positions are very clearly marked on the board. The remote control handset, which is included in the kit, comes ready assembled

My preference for tools is as follows: Antex CS 18 W soldering iron 22 swg solder for components and IC sockets 18 swg solder for the relays and connectors Small flat nose pliers Small side cutters Solder sucker (in case of mistakes)
		A ready assembled handset is included in the kit

Don't be tempted to use the wife's nail clippers instead of side cutters. Some of the component wires are tougher than you think and may leave permanent indentations.

There are 10 points to follow in assembling the kit, 11 if you include testing.

1. Resistors and diodes:
I would advise anyone to practice bending the resistors to the correct size using some spare resistors before locating and soldering the real ones. Because I'm red/green colour blind ("colour deficient" is a better description) I always put resistors across a digital ohm meter before bending or soldering. This is a wise precaution for anyone even with good colour vision.

Diodes always need a heat sink of some sort to prevent damage. I use a crock clip with a small amount of wet tissue clipped to the glass body of the diode and minimal contact with the soldering iron. (Force of habit always makes me blow vigorously on the joints and components afterwards to cool them.) The direction of the diodes is clearly marked on the pcb. Getting the resistors all the same way doesn't matter but it does make the finished article look better.

All component locations are very clearly marked

2. IC sockets:
Clearly marked on the pcb with small indentations to indicate direction. The sockets are in two parallel banks but the sockets in each bank face in opposite directions. I recommend placing the sockets in the pcb one at a time, inverting the pcb, sliding it on to the work bench and soldering one pin. Then lift the pcb and firmly press onto the IC socket and re-solder the pin. This enables you to get the socket firmly flush with the pcb. Then you can solder all the other pins in easily.

3. Resistor networks:
Only three, easily identified and placed.

4. Ceramic resonator:
Only one and the only thing that would fit in the space given. This is the first time I've heard them called this, to me and lots of other Radio Amateurs they are "crystals". No matter.

5. Switches:
Again only 3, one a "zippy tact" switch. New to me, but unmistakeable when you see it.

6. DC power jack and 7805 regulator:
The only care here is that the regulator pins need bending. Luckily or by design, they all need bending by the same amount, often the middle pin is slightly longer. There is little room for error, as the fixing bolt and hole also need to line up.

7. LEDs:
13 and each has a flat edge, which is also shown on the pcb. It's not easy to get this wrong.

8. Electrolytic capacitors:
3 only, positive leads clearly marked.

9. Terminal blocks:
12, solder in using the same method as for the IC sockets but use 18 swg solder. There are clear instructions to face the wire entry side outwards. These terminal blocks are of very good quality and will compress the wire firmly without cutting it like cheaper ones do.

10. Relays:
12 - same as for the terminal blocks except these will fit into the pcb only one way.

Testing
Checking that the components have all been located correctly and that there are no spare holes or components is a must. Done thoroughly, it can save you pounds and much time!
Then a 12v DC power supply is needed. I used the 13.8V supply from my Kenwood PS-430, as it just happens to have a flying lead with a suitable jack plug on it. The voltage measured at pins 10 and 20 of the 20 pin IC was 4.98V. After removing the power jack came the most difficult bit.

Inserting the ICs

Nearly there! Just the ICs and relays to insert.

I always ground myself before handling an ic.
I've never had any fail on me before and its not necessary for all types of IC but, as it takes so little effort, I always do it. However that was not the problem. The IC pins are slightly splayed (as they always are) and will not fit anywhere near the socket position.

The trick with this is to use a special IC inserter or failing this, place the IC on a firm flat surface with one set/side of pins flat on the surface. Very firmly rock the IC to bend all that set/side of pins inward a tad. Turn over the IC and repeat with the other set/side of pins. Check for a good match with the IC socket. Repeat the bending as necessary until a good match is obtained. (Using an IC inserter is much easier but may be considered cheating in some circles!)

After checking that the ics are in the correct way round and re-checking, then the power supply can be re-connected. If all is well then the hand control unit will work and switch the LEDs and relays as described in the instructions. (View the documention - Requires Adobe Acrobat)

I admit to having a fault with mine. I had completely failed to solder the + power pin on the IC for the 2nd bank of relays, just missed it completely. Consequently they didn't work. A careful inspection with a strong hand lens revealed this almost immediately.
After soldering that pin correctly, the unit performed flawlessly.

I was a little concerned that the regulator IC had no heat sink. I need not have feared.
I ran the unit for an hour with all relays on and the 7805 regulator only got warm.
I measured 392mA operating current with all relays on, and 33mA with all relays off. Measurements were made with a Cirkit TM 115 Digital Multimeter. These figures agree very well with those published by Quasar.

All in all, a very high quality kit with clear, unfussy instructions.

It will find many applications where individual items are required to be switched from a distance. I found that the hand controller would work from the next room as long as there was an unblocked and reflecting path between the hand controller and the unit. Quasar claim a range of 18m - this I can easily believe.

Finished board showing the 12 relays and connectors

Yes, it would be possible to switch on/off the table lamp or even the motor to open/close the curtains. However, Quasar quite rightly issue an emboldened warning about switching mains voltages, If you are not experienced, don't. It could be dangerous.

The printed circuit board has mounting holes at each corner for pillar fixing into a suitable box.

My Verdict:
My only niggle was the font size of the instructions.
Otherwise, this is an excellent, high quality kit with a myriad of uses.

		View this kit on the Quasar Electronics website
		Quasar Electronics stock a comprehensive range of electronics kits and projects. Check their website for details of the full range available.

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