Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
Hi, I am trying to use an NTE130 power transistor but I am not sure what to connect to. I know my input signal goes to the base, and I am guessing the collector/case goes to ground. Can anyone clarify this for me? Thanks
For a common-emitter amplifier, the input is fed to the base, the emitter is grounded for AC but not necessarily at DC ground. The collector is supplied from a Positive supply through a "load", either a resistor or a transformer winding. The output signal is developed across this load. The circuit has a voltage gain of -5 to -100, and has power gain. It inverts the input signal
For a common-collector amplifier, the input is fed to the base, the collector is connected to a Positive supply with no load between the collector and the positive supply. The collector is the AC ground for the circuit. The "load" is connected between the emitter and the negative end of the collector supply. The circuit has a voltage gain of <1, but can have substantial power gain.
Are you following a published circuit, or are you concocting one of your own?
The 3055 is being used as a switch, not an amplifier. The circuit you show is very poorly designed. The 10k resistor between pin 3 of the 555 and the base of the transistor is much too high in value. This causes the base current to the 3055 to be much too low when it is turned on, preventing the 3055 from turning on hard enough to minimise power dissipation when it is turned on. It needs to be mounted on a heatsink.
You seem to be confused about how to mount a TO3 NPN power transistor. You need to buy a "mounting kit" consisting of a mica washer, teflon bushings, which allow you to mount the transistor on a grounded metal heatsink by preventing the case from shorting to the heatsink.
What is the circuit supposed to do? What is the coil?
I have the washer and bushings, the heatsink is on the way. What resistor should I use? The circuit varies the frequency of the coil between 8 and 26Hz, which it gets from another circuit and divides by 1000 with the CD4059A. How do I connect the NTE130? Thanks.