INSTRUCTIONS FOR USE LED-Thermometer Part No.
Imprint These instructions for use are published by Conrad Electronic GmbH, Klaus-ConradStraße 1, D-92240 Hirschau. All rights including those of translations reserved. Reproduction of any kind e.g. photocopy, micro-filming, or entry in EDP systems requires a prior written permission of the publisher. 100% recycling paper Reprinting, even in parts, is prohibited. These instructions for use conform to the state-of-the-art technology at the time of printing. Subject to changes in technology and equipment.
Important! Must read! The warranty claim becomes null and void in case of damages arising out of nonadherence to the instructions for use. We do not assume any liability for consequential damages caused by this. Table of contents Page Operating conditions…………………………………………………………………………….3 Intended use……………………………………………………………………………………...5 Safety guidelines…………………………………………………………………………………5 Product description………………………………………………………………………………7 Description of circuit……………………………………………………………………………..
• The device can be operated in any position. • The permissible ambient temperature (room temperature) may not fall short of or exceed 0°C and 40°C respectively during operation. • The device is intended for use in dry and clean rooms. • In case condensation takes place, an acclimatisation period of up to 2 hours must be given.
Safety Instructions While handling the products that come in contact with electrical voltage the valid VDEguidelines must be observed, especially VDE 0100, VDE 0550/0551, VDE 0700, VDE 0711 and VDE 0860. • Before opening the device always pull out the plug or make sure that the device is completely without current. • Components, assemblies or devices may be started up only when they have been fitted, completely insulated, in a casing. While fitting they must be completely devoid of current.
• If measurements are unavoidable with the casing open, then an isolating transformer must be interposed, or, as already mentioned, the power must be supplied through a suitable mains unit (that conforms to the safety regulations). • All wiring work must be done in dead state. Product description An electronic thermometer with 13 mm red LED-display. This thermometer can be used at all places, where temperatures are to be measured from -50°C to +150°C with a high degree of accuracy.
However, since we are deriving here the voltage to be measured from the voltage divider R7/ KTY10, there are only positive signals. We displace the zero point by artificially laying “high” the measuring input 30 above the wiper of P2 (vis-à-vis the reference at 32 & 35). The IC rates everything that lies below the artificial reference level at pin 30 as minussignal and activates the negative sign.
the reference value and the offset are, the lower will be the error; in the ideal case it is zero (but only at this reference temperature!). Technical data Operating voltage……………: 7 ... 18 V= Power consumption…………: approx. 200 mA Measurement range………….: -50.0 to +150.0°C Resolution……………………..: 0.
If everything is OK here, then the next place to look for a possible fault is a cold solder joint. These unpleasant things while tinkering occur when either the solder point was not heated properly, so that the tin comes properly in contact with the cables, or when the joint was moved while cooling at the time it was just setting. Such faults can mostly be detected at the matt-look of the surface of the solder joint. The only solution here is to solder the joint once again.
2. Only electronic tin SN 60 Pb (i.e. 60% tin, 40% lead) with a colophony core may be used as soldering material, which at the same time also acts as soldering flux. 3. Use a small soldering iron with max. 30 watt heating power. The soldering tip should be tinder-free, so that the heat can be discharged properly. This means: The heat from the soldering iron must be conducted properly to the point to be soldered. 4.
Thereafter, the excess wires are cut away. Note that this circuit is equipped with two different types of resistors. The commonly used resistors are the carbon film resistors. They have a tolerance of 5% and are marked by a gold-coloured “tolerance ring”. Carbon film resistors normally have four coloured rings. Metal film resistors have a tolerance of just 1%. This is shown by a brown “tolerance ring”, which is imprinted a little broader than the remaining four colour rings.
Caution! Depending upon their make the electrolytic capacitors show different polarity markings. Some manufacturers mark “+”, others “-“. The polarity specification printed by the manufacturer on the electrolytic capacitor is important. C1 = C2 = C3 = C4 = C5 = C6 = C7 = C8 = C9 = 1.
1.6 Spindle-trimmer potentiometer Solder now both the spindle-trimmer potentiometers in the circuit. P1 = 100 k P2 = 100 k 1.7 LED seven-segment displays Set the LED-displays in the 40-pin IC-socket. See to it that each of the decimal points are below.
1.9 Integrated circuits (ICs) Finally, the integrated circuits are inserted in the openings provided with the correct polarity. Caution! Integrated circuits are very sensitive to incorrect polarity! For this reason, pay attention to the corresponding marking on the ICs (notch or point). The component IC 2 is an especially sensitive CMOS-IC, which can be destroyed through static charge. MOS-components should thus be gripped only at the casing, without thereby touching the contact pins.
1.10 Final check Before starting-up, check the printed circuit board once again that all the components have been inserted properly and with the correct polarity. Check on the soldering side (the side with the conducting pathways), whether the conducting pathways have been bridged by the remains of the soldering tin, which can lead to short-circuits and to a destruction of the components.
Component diagram 2. Construction stage II: Connection/start-up 2.1 After the components have been placed on the printed circuit board and the board has been checked for possible faults (cold solder joints, solder straps, etc.), a first functional test can be conducted. 2.2 Bring both the trimmer potentiometers in the middle position. 2.
2.5 A screened direct voltage of approx. 7 – 18 V= is applied to the solder pins marked with “+” and “-”. It must be noted that the power supply unit used must conform to VDE-regulations. 2.6 Depending upon the wiper setting the spindle-trimmer will be pointing to some temperature. 2.
Is a cold solder joint available? Please check each solder joint thoroughly! Check by using a pair of pincers, whether the components are wobbling! If you suspect a solder joint, then solder it again to be on the safe side! Also check that each joint is soldered; it often happens during soldering that joints are overlooked. Also keep in mind that a printed circuit board soldered with soldering fluid, soldering grease or inappropriate soldering tin cannot function.
the help of P1, and the equalisation thus comes to an end. In order to achieve the maximum accuracy, the 0° and 100°C equalisation must be repeated. The selection of the equalisation method also depends upon the later use. For instance, if temperatures are to be measured mainly in the living area (below 50°C) the method with the clinical thermometer is more appropriate, because it covers these temperatures in a better way. If temperatures above 50°C (0°...
• in case of arbitrary changes in the circuit • in case of improper placement of components not intended in the design, free wiring of components like switches, potentiometers, sockets, etc.
