![]() I am so close to finishing a year long project and this is one of the last things I need to figure out.Īlso if anyone needs any further information please ask. Could I use a transistor to replace the optoisolator? Would this transistor work: Also can I use a 1.5k resistor instead if 1k? Any help would be greatly appreciated. However when I connect the wires to an optoisolator on my board it doesn't activate.(I tested the optoisolator with a multimeter and it is working fine) It seems like maybe the optoisolator isn't the best solution anyways since I don't think I really need the isolation(keyfob runs off of a 3.3v battery). I already opened it up and set it up so i have four wires(two per button for two buttons) and it works if I tap wires together(I also have a 1.5k resistor on the end of one wire for each seemed like a good idea? lol idk). I’m guessing that you saw my earlier post about EasyEDA in this thread:īut if not there’s a bit more background to it there.Hello, for my project I need to simulate pressing a button on my car's keyfob. I have a schematic in which there is one opto-coupler (O1)named TCMT1100 not available in the TINA library. It is a buck converter that converts 110Vdc into 5Vdc,2A. that can be used as USB charging device for smartphones. The spice model is available for this device (but has not gone into EasyEDA yet). I am using Texas Instruments TINA simulation software. To try to make a 10MHz – 20MHz bandwidth galvanically isolated (AC coupled) high impedance scope probe.įor lower frequency precision isolated DC amplification? I’m looking at optoisolators and optocouplers at the moment because I’m tinkering around with a hybrid of this: ![]() That isn’t specified in the datasheets either. While it provides no isolation, the transfer function is identical. To make test and evaluation easy, I used a single dual op amp and only one 12V supply. R4 is adjusted so that it drops about 2V at maximum signal level –this is very non-critical.Ĭ1 is a compensation capacitor –for faster performance, this may be adjusted down –if too low, the circuit may oscillate. Potentiometer R4 accommodates gross variations in the CTR (both devices). The easiest way to test performance is to connect a DVM between input and output. Adjusting R2 so that R1 + R2 ✴.7K causes the output of U2 to come close to the input voltage signal –further adjustment of R2 will trim for the difference in CTR so that the output voltage will exactly match the input voltage. At the same time the output of U3A presents a positive going signal to U2. When both op amp inputs are equal, the output of U1 stops integrating. ![]() U3-B turns on and provides a positive going feedback signal. At any rate, the LM358 is very inexpensive.Ī positive signal input causes the output of U1 to shift positive. There is the LM321 single op amp, but it is unpopular and comes only in the SO-23-5 SMD package. I do this because there is no DIP single device that will do the job (that I know of). ![]() I generally use the LM358 dual op amp whenever I need a single ground sensing op amp. As their name implies, opto-isolators transmit signals between two circuits with light. Opto-isolators Opto-isolators are integrated circuits for transmitting signals and information between two separate circuits without ever connecting them electrically. To maintain a high voltage rating, use two single devices and match the CTR to some degree. using opto-isolators to connect several separate instruments and circuits together. While DIP optical couplers have up to about 5kV isolation capability, this circuit cannot support above about 100V or so because one of the outputs is fed back to the input amplifier –this puts the voltage isolation between adjacent pins on the device rather than across the device. ![]()
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