I was using 555 astable output and connect to a radio transformer ( 1:70), trying to step up the output voltage from pin 3. Somehow I could not measure any output from the secondary coil of the transformer. Is there anything wrong with this set up?
What is this "radio transformer," what frequency are you using and how are you driving the transformer -- did you attempt to drive it directly from pin 3, or did you use a switching element such as a transistor or a mosfet? You didn't say.
The frequency is set at 1K Hz, I use a mini transformer ( the input has two wires and out put with 3 wires, input is 1 ohm and output 72 ohms, it appears like a cube measuring 1cmx1cmx1cm). As I need only high voltage and low current, I drive the transformer direct from pin
I can measure output from pin 3 using a multitester, I connected a LED to the output after a resistor it lights up.
Did you use a breadboard? If so, it's easier to troubleshoot. I'll assume you can swap components easily. At 1kHz you will not be able to see an LED turning on and off. When you need to build a timer circuit at some frequency that is too high for the naked eye to perceive, you have a couple of options. One of my favorite tricks is to take a radio and set it to a blank spot on the AM dial. If you hear a buzz on the radio when you turn the 555 on, that means it's working. Another way is to replace your timing cap with one that's big enough to give you a frequency of about 10 Hz or 1 Hz, or something on that order. If it makes an LED blink, you know it's working; then you can swap the timing cap back to the design value, for 1kHz. You can be pretty sure it will work with the new cap, since you didn't change anything else. Once you have made sure the timer is working, you can go on to the rest of the circuit.
Possibly the one ohm primary of the transformer is too heavy a load for the timer. Bogging the 555 down with such a heavy load might be causing the output to malfunction. You may be able to improve performance by putting some resistance in series with the transformer primary. But I would be inclined to use a transistor to drive the transformer.
You need to add a resistor between pin 3 and the transformer primary. Divide whatever voltage you are using to power the 555 by .15. Use the standard value resistor closest to that number.
You may get some pretty high voltage at the secondary. I would recommend you run the 555 at no more than 5 or 6 volts. You don't know how much voltage the insulation on the wires on the secondary can withstand.
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.