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Member Since: January 30, 2013

Country: United States

  • Sharp has changed the package for this device, and this particular version Sparkfun is selling is the older, prior design. The new form factor (P/N S202S02F) fits a TO-220 heat sink perfectly, whereas this older design not as well. Same specs otherwise. I use these with no heat sink for loads under 2 amps. Work great. If you want to make your own “marginal” heat sink, cut a small piece of extruded aluminum angle or C-bar and adhere it on. IMO don’t go 8 amps with these, stay below 5 amps (use a heat sink above 2 amps).

  • This particular model only turns on during the times when the AC voltage is at 0 v, which is twice per cycle, or 120 times a second. Commanding the device on and off 10 times a second is not a problem at all.

  • I am trying this. I ordered 2 pads. My plan: An Arduino PWM output driving a power mosfet with 9V DC to the two heat pads connected in series, so that each pad is 4.5 V. The heat pads will be taped around a 2-inch dia PVC pipe to create a heated tube hide for snakes.

    I have always wanted to do this, but not with 120 VAC heat tape/heat pads normally sold for reptile heating. But I do not mind putting 9V inside the cage.

  • If you want to opto-isolate with this optoisolator, you will have to invert the output by driving a PNP transistor rated above the relay coil current, or use a similar mosfet device that drives hi-side loads. I would not drive relays directly with these optoisolators. Another option is to use the optoisolator, pull the output up to Vss with a resistor, and use that to input a regular CMOS inverting buffer. Then, connect the ouput of the buffer to the ULN2308 darlinton driver described below.

    I had a very similar application. I ended up not opto-isolating, and I used the ULN2308 Darlington driver chip (sold here and on Adafruit). The chip is nice because it is 8 channel and already has input resistors. You just connect an Arduino output to a ULN2308 input channel. The corresponding output is a “sink” which will easily handle a 12V relay. The ULN2308 I have already has back-emf diodes in it, which is a plus. The drawback is that your Arduino ground and your car ground have to be tied together.

  • You said it best. 60/40 is crap compared to 63/37. This is good solder.

  • The back EMF diodes should be as close to the relay coil as possible. Although it is always a pain to have to add diodes at the relay, that is the best way. Even if the relay is only 6 inches away from the mosfet driver, it is still better to have the diode at the relay.

  • The best way to drive the relay from an Arduino is to use a transistor (or other driver), rather than driving the relay directly. Also, connect a diode across the relay coil close to the relay. The cathode of the diode (the end with the line on it) connects to the coil +. The anode of the diode connects to the coil -. Hope this helps.

  • This is a nice sensor to learn about A/D manipulation with uC’s. Don’t know if anyone else has experienced this, but when used remotely even less than 3ft, the noise susceptibility makes Vout will jump around by a few mV. I placed a 680 Ohm resistor in series with the output per the datasheet suggestions, and it helped somewhat but did not get rid of enough noise. Tried capacitors between Vin and Gnd, no change. Tried sampling 5 times then averaging the result - not good enough. Did not try shielded cable.. instead I got the DS18B20 and never looked back. (Not sure if the noisy signal of the TMP36 is a result solely of the Arduino or of the remote cable length. By noisy, I mean typically +/- 1 deg F bounce - too much for a temperature controller for a sensitive application.)

  • OK, I was lauding the effectiveness and simplicity of the TMP102 just a few weeks ago.. then I tried the DS18B20. Every bit as stable as the TMP102 but in a nicer package for remote sensing (I just bought the probe version to make it easier.) Excellent sensor. The extra code involved is actually not that bad. The newest library works perfectly. The DS18B20 is well-suited for temperature controller applications with Arduino and such. I am using it in an egg incubator, and it holds temperature very well.

  • Yes it does. You can place the pullup at the Arduino or close to it, between 5V (or 3.3 if your Arduino is 3.3V) and the DQ pin of the sensor. This sensor works very well. It is stable even with a longer cable.

    My first application used the TMP36. I quickly abandoned that sensor. While it is good for monitoring a temperature inside an enclosure, it is too susceptible to noise when remote. The DS18B20 on the other hand is awesome for remote sensing and is offered in a nice probe for you. All that extra code is well worth it.

No public wish lists :(