Fullscreen HTML5Med Res (??MB)HTML4

TOUCH and/or REMOTECONTROLLED LIGHT DIMMER Last month, we covered the design and board assembly of our new Light Dimmer. This month, we complete the construction, detail the touchplate and pushbutton extensions, and describe the test procedure. Pt.2: By JOHN CLARKE O NCE YOU HAVE completed the assembly of the main PC board (see Fig,3 last month), the metal contact screw can be installed as shown in Fig.7. This done, cover the exposed end of the contact screw, the nut and the surrounding PC board area with a generous coating of neutral-cure silicone sealant, so that there is no exposed metal on the component side of the PC board. Smear the silicone sealant on with a wet spatula and make sure it adheres to the surface of the PC board. Apply a second coating if necessary. The ends of the 4.7MΩ resistors should be cut off flush with the top surface of the PC board. These resistor ends and the surrounding board area should also be covered with silicone sealant, so that the mains cannot possibly directly short against them or the metal contact screw. Extension circuit The extension circuitry is relatively compact – see Fig.8. In its simplest 60  Silicon Chip form you can use a momentary contact mains switch which closes the Active and EXTN terminals when pressed. Alternatively, you can use another touchplate extension unit which includes the 4.7MΩ protection resistors and a few other components. The touchplate extension operates as follows: if the touchplate is not touched, Q1 is held off via the 1MΩ resistor between its base and emitter. If the touchplate is touched and the Active is above ground, Q1’s base is pulled low via D1 and the 2.2MΩ resistor. This switches on Q1 and the EXTN connection is pulled to the Active. This will operate the main dimmer circuit in the normal way. The .01µF capacitor acts as a filter and prevents sudden transients from driving Q1. Zener diode ZD1 protects against excessive voltages at the cathode of D1. This zener and the 220Ω resistor at the collector of Q1 provide protection if the connection to the main circuit is reversed. In this case, ZD2 will be forward biased (thus protecting Q1), while the 220Ω resistor provides current limiting. Construction The extension circuit is built on a PC board coded 10101022 and measuring 52 x 72mm. As with the main dimmer board, it is installed into a Clipsal blank plate with a blank aluminium touchplate. Fig.7: this cross-sectional diagram shows how the metal contact screw is mounted so that it makes contact with the aluminium touchplate. This arrangement is the same for both the main unit described last month and the extension board. Note the silicone sealant over the end of the screw and the nut (see text). www.siliconchip.com.au The completed dimmer will mount to a metal wall box where fitted in a brick wall but it must be spaced from this using a 30mm or deeper mounting block (otherwise the circuit may make contact the metal box). It can be mounted directly to a stud (Gyprock) wall using standard mounting hardware. Alternatively, it can be placed on a thin or standard surface-mounting box. Once again, begin by checking the PC board against the published pattern to ensure there are no shorts between tracks or any breaks in the copper. Repair these as necessary. Now check that the holes are drilled to the correct size for the larger components. The screw terminal mounting holes need to be 1.5mm in dia­meter, while the PC board mounting holes and the touchplate connection should be 3mm in diameter. The resistors, zener diodes, the di- Fig.8: here are the circuit diagrams for both the touch-controlled dimmer extension (top) and the simpler pushbutton extension using a mains-rated momentary switch. NEUTRAL CURE SILICONE SEALANT NYLON SCREW This photo shows how the contact screw and nut and the 4.7MΩ resistor holes are covered with neutral cure silicone sealant. Do the same for both the main dimmer board and for the extension board shown below. ode and transistor can now be installed on the PC board. The parts list shows the resistor colour codes. Alternatively use a digital multimeter to measure each value. Make sure that the two 4.7MΩ VR37 resistors are placed in the correct position and don’t substitute for these components. These are high-voltage INSULATE INSIDE RED BORDER WITH NEUTRAL CURE SILICONE SEALANT – SEE TEXT. NYLON SCREW The completed touchplate dimmer extension mounted in its Clipsal blank plate. The lowest terminal on the three-way block is not connected to anything; it is the equivalent of the “loop” terminal on a conventional light switch. Note that all exposed metal parts inside the red boarder must be insulated with neutral-cure silicone sealant, as shown in the top photograph. www.siliconchip.com.au Fig.9: the PC board parts layout for the touchplate extension. Note that the two 4.7MΩ resistors must be Philips VR37 high-voltage types (do NOT substitute). They are mounted on the underside (ie, the copper side) of the PC board. February 2002  61 ELAN Audio The Leading Australian Manufacturer of Professional Broadcast Audio Equipment Featured Product of the Month PC-BAL PCI Format Balancing Board Interface PC Sound Cards to Professional Systems Not only do we make the best range of Specialised Broadcast "On-Air" Mixers in Australia. . . We also make a range of General Audio Products for use by Radio Broadcasters, Recording Studios, Institutions etc. And we sell AKG and Denon Professional Audio Products For Technical Details and Professional Pricing Contact Elan Audio 2 Steel Crt South Guildford WA 6055 Phone 08 9277 3500 08 9478 2266 Fax email sales<at>elan.com.au WWW elan.com.au Subscribe & Get this FREE!* *Australia only. Offer valid only while stocks last. Parts List: Pusbutton & Touchplate Dimmer Extensions Pushbutton Extension 1 Clipsal CLI31WE architrave plate 1 Clipsal CLI30MBPRWE ‘Press’ momentary contact switch Touch Plate Extension 1 PC board, code 10101022, 52 x 72mm 1 Clipsal CLIC2031VXBA blank aluminium plate and blank plate 1 3-way PC screw terminal block (Altronics P 2102 or equiv.) 1 M3 tapped x 6mm metal spacer 2 3mm x 6mm untapped spacers 2 M3 x 16mm countersunk Nylon screws 1 M3 x 15mm countersunk plated metal screw 3 M3 nuts Neutral cure silicone sealant Semiconductors 1 BC559 NPN transistor (Q1) 2 6.8V 1W 10% zener diodes (ZD1,ZD2) 1 1N4148, 1N914 signal diode (D1) Resistors (5%, 0.25W unless stated) 2 4.7MΩ 1W VR37 Philips high voltage resistors (no substitutes) 1 2.2MΩ 0.25W (red red green gold or red red black yellow brown) 1 1MΩ 1% 0.25W (brown black green brown or brown black black yellow brown) 1 220Ω 1W (red red brown gold or red red black black brown) resistors that are rated at 2.5kV RMS and are specified for safety reasons. They are light blue in colour and are mount­ed on the underside of the PC board. Their leads are then cut off flush with the top surface. The capacitor can be installed now, as well as the 3-way terminals. The mounting screws and the metal contact screw are installed in exactly the same manner as for the main dimmer unit. As before, use neutral-cure silicone sealant to cover the end of the metal contact screw, its nut and the ends of the 4.7MΩ resistors. Testing THAT’S RIGHT – buy a 1- or 2-year subscription to SILICON CHIP magazine and we’ll mail you a free copy of “Computer Omnibus”. 62  Silicon Chip Your next step depends on how confident you are of your construction. You could install the dimmer in the wall if you are supremely confident that you haven’t made any mistakes but for the rest of us mere mortals, it’s probably wisest to check the operation first using a low-voltage AC transformer and a 12V light bulb. This requires a bit of mucking about but it is the safest option. Note that if you don’t go the low voltage route, the components are live when it is wired up to the mains and so the plate must be securely located onto a wall before power is connected. By law, you must have a licensed elec- trician do this for you and of course, the power must be switched off at the fusebox to install the unit. Before installing the unit though, carry out the following safety check. Switch your multimeter to its highest range and measure the resistance between the Active terminal and the touchplate contact screw. The resistance should be close to 10MΩ, or there should be negligible pointer deflection if you have an analog multi­meter. Do this for both the main dimmer and for any touchplate extensions. The test will ensure that there is no fault at the touchplate. If the circuit fails this test, check that the correct value resistors have been used. The method of connecting up the circuit using the transformer is shown in Fig.10. You will need a 12V 1.2W bulb and a transformer which delivers about 15V at 200mA or more. We used a 2155 type and powered it from the mains via a mains terminal block and power lead. The earth wire connects to the transformer body. Operation of the power supply and zero voltage detection is provided via the separate lead connections to the 1kΩ resistor and the 680kΩ resistors respectively. You will need a 220Ω 1W resistor for the supply lead connection to the 1kΩ 5W resistor and the .01µF www.siliconchip.com.au Fig.10: this temporary test setup is the way we recommend you test your dimmer. A couple of components need to be changed to allow it to operate at low voltage but it’s much safer than working on a live circuit. As mentioned, this won’t check the operation of the touch switch but it will check the infrared remote control functions. capacitor needs to be changed to a .001µF (coded 1n0 or 102). This capacitor will prevent the phase control running into the next half cycle due to a shift in the zero voltage detection point caused by the lower voltage operation. The range of phase operation is not the same as for mains voltage operation but is sufficient for test purposes. Note also that the touch input will not operate with this low AC supply and any dimming control will need to be done with the handheld remote or by momentarily shorting the EXTN and A terminals together using a momentary switch, or by simply touching two wires together. Measure the power supply voltage at the anode of D2 and the cathode of ZD1. Note that measuring the zener www.siliconchip.com.au diode voltage across ZD1 will give a reading of around 2V as this diode is being switched to conduct in the forward and reverse directions with the alternating supply voltage. Gate trigger pulses can be measured at the point shown. The trigger pulses can be seen with an oscilloscope, with locking of the trace set by the line lock (available in the oscilloscope trigger options) or by a probe connection to pin 6 of IC1. The remote control decode, start/ CORRECTION The specified Triac in the main dimmer unit should be an SC141E 6A 500V Triac (not an SC141D). stop and tracer signals are available at pins 8, 1 and 7 respectively, while the remote control signal from IC2 can be monitored at its pin 1 output. Remember to replace the .001µF capacitor with the correct .01µF value whent testing is complete, before operating the dimmer on the mains! Remote controls The default setting for the remote control coding is with both pins 2 & 3 of IC1 connected to the 0V rail. This sets the code that the dimmer will respond to as TV1 using the RC5 code system. The following instructions apply to the Jaycar Big Shot 3 and Select 1 preprogrammed infrared remote controls. If you are using a different type of “programmable” infrared controller, February 2002  63 Specifications Phase angles (typical)............................ Minimum brightness 152°; maximum brightness 34° Touch Dimming...................................... < 60ms no change; 60ms-640ms on or off; .............................................................. > 640ms dimming Last setting to full brightness................. 2.5s Dimming rate ........................................ 3s from minimum to full or full to minimum brightness Dimming steps ...................................... 102 from minimum to full brightness Soft start ............................................... 340ms from off to full brightness Remote control...................................... Code options 4 (RC5 code TV1, VCR2, SAT1 and SAT2) Fast up dimming (CH +) ........................ 2s from minimum to full brightness Fast down dimming (CH -) .................... 2s from maximum to minimum brightness Slow up dimming (VOL +) .................... 11.6 seconds from minimum to full brightness Slow up dimming (VOL -) ..................... 11.6 seconds from full brightness to minimum Instant off ............................................. Mute Dimming steps ...................................... 102 Mains frequency lock range .................. 45 to 55Hz Mains frequency for remote control to operate .................................. 47.5Hz to 52.5Hz Triac gate drive ...................................... 80µs at 50mA Brown out reset voltage for IC1 ............ 4.68V (<at>120VAC mains supply typical) Maximum lamp wattage......................... 250W you can find the correct code by trying the codes in the instructions that apply to Philips brands of equipment. You should be able to find one that will operate the dimmer. If you are using the Big Shot 3 remote control you need to set it to code 191. This is done by pressing the SET and TV buttons together and then releasing these buttons. The transmit LED will light. Now enter the number 191 using the number buttons on the remote control. The Select 1 remote control must be set to code 11414. Press both the CODE and Operate (red) buttons for two seconds and then release them. Enter the numbers 11414 using the numbered buttons. The Select 1 remote control will only operate the dimmer when it is set for the TV1 code. The remaining code options using pins 2 & 3 on IC1 are for use with the Big Shot 3 or similar remote control. You only need to use another code if the TV1 code transmission also operates another remotely controlled item in your house. Alternatively, if you have more than one dimmer in the vicinity, you can use a different code for each. The “Code Options” table shows the codes for each of the options. Changing the code means that the thin tracks that tie pins 2 & 3 to the 0V rail may need to be broken with a knife and re­soldered 64  Silicon Chip to the +5V rail. For example, the SAT1 code needs the pin 3 connection to be broken and soldered to the +5V rail. The Big Shot 3 transmitter will also need to be changed to the new code. For SAT1, press SET and SAT together and then enter code 424. Note that you do not need to program the value into the SAT button selection. It could be entered using the VCR or TV button selection instead. To operate the remote dimmer, you need to select the button (TV, VCR or SAT) that the code was entered into. If you select the VCR2 code for the Big Shot 3, it does have an error in its transmission for the MUTE function. We decode this erroneous transmitter code to provide the Off function for the dimmer so that the control operates correctly. However, the VCR2 coding will probably not operate on Mute for a different brand of preprogrammed transmitter. So it is probably wise These are the “Select 1” (left) and “Big Shot 3” remote controls from Jaycar Electronics. Other remote controls that can be used include the Dick Smith Electronics Cat. G1223 and Altronics 8-In-1 (Cat. A1007). www.siliconchip.com.au to avoid using this code selection unless the other codes conflict with other remotely operated equipment. We did not use the VCR1 coding instead (which has correct transmission coding for the Mute) because its Mute code is the same as the Mute code for the TV1 setting. This is called a punch-through code which allows muting of the television sound while still set to control the VCR. Installation First of all, have you remembered to change that .001µF capacitor back to 0.01µF? Do it now if you haven’t! The dimmer circuit is easily installed into an existing dimmer or switch circuit because the wiring is the same using the Active (brown or red) and lamp-via-neutral (blue or black) wires. The extension wiring requires an Active connection for the extension unit and an extension wire which connects to the EXTN input on the dimmer. It can be installed into existing 2-way switch wiring or you can have an electrician install the wiring if this is not already present. The loop terminals on the dimmer and extension are free to terminate any wires that require connecting together but are not part of the light switching. This is to duplicate the loop terminal provided on standard light switches. We PLEASE NOTE! These codes suit the two recommended infrared remote controls. Other controls may work but the code setting options may be different. You will need to set the codes accordingly. show below the typical 2-way switch wiring and how to wire up the extension to the dimmer. You can use either a momentary contact switch or the extension touchplate dimmer to provide dimming from a remote position. The momentary switch can be used in an architrave switch surround, making it easier for installation where space is limited such as in a door surround. Note that the dimmer plate normally runs just warm to the touch, due to the dissipation within the Triac and inductor when it is driving the lamp, the 1kΩ 5W resistor, the zener diode and any losses in the 0.1µF and 0.47µF mains capacitors. The remote control must be directed toward the receiver on the main dimmer plate to obtain reliable operation. We obtained a reliable 7m control range for our prototype. SC This circuit operates on the 240V AC mains and most parts of the circuit are at mains potential and therefore DANGEROUS. Furthermore, installation into fixed wiring can only be undertaken by licensed electricians under current legislation in most states. This is the Clipsal CLIC2031VXBA blank plate (above) which we used for the dimmer and extension circuits. Fig.11: the top diagram shows typical 2-way domestic light switch wiring, with two conductors between the switches. Installing 2-way dimmers should allow the existing cabling to be used, albeit rearranged. The momentary contact switch must be mains rated and of robust construction. www.siliconchip.com.au Fig.12: this is the full-size PC board artwork for the dimmer extension. The main PC board pattern was published last month. February 2002  65