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  1. KTW

    Temperature sensor

    I've made an emissions system smoker and the temperature control didn't come with a heat resistant probe so I purchased one but it didn't match the original probe. I added 10.5k resistors to match the ambient temperature of the original but it is stuck on 23.5oC. Does anyone know if I can get...
  2. KTW

    PIR and LDR light circuit

    I put this together and it works just the way I want but it may need tweaking if I missed something. Anyone see a problem with this as is? Thanks.
  3. KTW

    Is this an inductor?

    I'm trying to test a few components and this one is marked 393JM which should be an inductor according to the data sheet but I can't find an image of this on line. Can anyone confirm the identity? Thanks.
  4. KTW

    Resistors or not?

    Does anyone know if these light panels have resistors built into them or do they even require them? Thanks.
  5. KTW

    Alarm Dilema

    I have built this alarm and it works well on the bench but with the alarm stationed in the house and the power, key and switch extended to the garage it goes into alarm after several hours of being switched on. I have used another duplicate alarm and have tested the magnetic contacts and the...
  6. KTW

    Base resistor from PIR

    Hi; I've made a similar circuit and omitted the base resistor prior to finding this schematic. The circuit will operate an LED string around 14 watts, the power source is 2 amps and the transistor that requires the base resistor is a bc547, the voltage is 9 volts DC. The output for the PIR is...
  7. KTW

    U8 spy camera

    I have a U8 spy camera and it won't charge via USB charger and video record at the same time although it should. The battery mode seems to over ride the external charging and the video function won't work. I'm wondering if removing or disconnecting the battery might allow the external charger to...
  8. KTW

    LCD SLF8384E

    I'm searching for a LCD with SLF8384E stamped on the back. Not having much luck so far. The display is from a Construction Master calculator and is about 5cm long by 2cm wide. There appears to be some separation and I tried heating it up but it's not working.
  9. KTW

    mini christmas lights

    I have a set of 2.5 volt tree lights with a few bulbs burnt out. I have replaced several and have some working but some refuse to co-operate. The sockets have been tested at 2.2 volts, the bulbs will light when 2.4 volts is supplied directly to them and when I connect the bulb leads directly to...
  10. KTW

    Thermistor Temperature Sensor

    I have a temperature control that reads one degree lower than the trigger temperature setting and I'm wondering if there is a method to have the sensor adjustable to calibrate it to the control? If the trigger is set at 15C it doesn't trigger until it reaches 14C. Does the one meter of wire add...
  11. KTW

    Defective PCB/scroll saw

    Hi guys, I have scroll saw that had variable speed now it only operates on high rpm. The switch is ok. Is there something specific I should be looking at testing on the board? I checked the triac and it's good. Thanks. Kevin.
  12. KTW

    Should a 555 timer ever get hot?

    I wired up two different 555's to a circuit, one and then the second after removing the first and both of them got really hot to the touch. I thought I may have fried the first one so I tried the second and the results are the same. Is there a way to test these?
  13. KTW

    220 vs 120 house voltage

    I've been looking at a shaver on Amazon that is advertised as being 220volt and 50HZ. Several people are telling me it works in 120 volt 60HZ outlets in North America. Any opinions on this?
  14. KTW

    I can't see how this will work

    I found this schematic somewhere and in looking at LED#2 on the right with the photoresistor wired in parallel how could it possibly control the LED when the LED is wired in circuit with the power source? I would think the light would stay on day and night.
  15. KTW

    Help with transmit and receive sending

    I'm looking at this transmitter and receiver for a signaling device. I would like the transmitter to work off a 3 volt output from a PIR and send a signal to the receiver which operates a buzzer but the output from the receiver is a data signal. I have two problems, one with signaling the...
  16. KTW

    Magellan 2000 GPS

    I am looking for a schematic for a Magellan GPS 2000. It stopped working several years ago and I replaced it with a Garmin. A common problem with this unit was it eventually stops acquiring satellites. Now the display doesn't work. The unit is outdated and I was just going to tinker with it, I...
  17. KTW

    interupting a circuit

    What device could I use operate a 9 volt buzzer and then quit or possibly reactivate after 3-5 seconds?
  18. KTW

    PIR light circuit

    Hello, I'm building a 12 volt 48LED light panel circuit that will operate off a PIR sensor with a 9 volt DC power supply. There will be a LDR built into the circuit so the light stays off during the day. I'll have a npn transistor within the circuit so I'm trying to determine the value and...
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