well the guy that orginaly designed it for me told me to start of with a 4.7 ohm 5 watt resistor between the igbt and the opto he then said to try going up or down with the resistor till i got my desired result he told me less resistance shold turn it of faster

i could hook the opto directly to the 555 but i wouldnt no what to use i dont know any thing about this stuff

i traded with guy to make this for me i did my part and he screwed me

all i had was what he drew me and how he described it from memory


also mik3 cool audio spectrum analizer

 

I read the datasheet of the opto and at first they say the maximum input current is 25mA but later they recommend the maximum input current to be 16mA. I think you have destroyed the LED at the input of the opto. Use a 350 ohm resistor instead of a 270 ohm.
What is more, with the 4.7 ohm resistor the maximum current which can flow each time a positive pulse is applied is about 3 Amps. In the datasheet says the maximum current the device can provide is 2 Amps, thus probably the output transistor is burned (failed short and that is why you read always 13.5. Use a 10 ohm resistor.
Also, you can't put two 7815 in parallel, they will exchange current between them if their output voltage is not exactly equal. You need to put a 470uF capacitor on the output of the 7815.
Generally, you need a complete redesign!!!

Thanks about the comment for my spectrum analyzer.

 

i messed around with resistors and got the 555 to the opto to work with out the hex inverter i used 1k 510 ohm and 2 220 2 k was to much now the opto has perfect square wave out put i removed one regulator as you said and installed a 470uf cap it still is putting out sqaure wave will the igbt switch on with only one amp

the igbt is turning on its just a matter of getting it to switch off faster now

 

Post your new circuit to see what have you done.

 

i attached an updated drawing mik3

 

I think you have the 7815 connected in reverse according to the scan0002.pdf version of your circuit.

 

What is the load you want to drive? Isn't just a coil?

 

Worse, there's no rectifier off that transformer secondary, so the 7815 is running on AC. And shouldn't there be some passive components around the LM555 for the timing?

Why not run the 555 off the +15 (assuming that gets straight) and just have the output drive the IGBT? Add a pullup resistor to +15 and that should work.

 

Ohh yes, Beenthere is right. I didn't realize it but a rectifier has to be placed before the 7815 other wise the 7815 won't work properly.

 

i forgot to add the rectifier for the 7815

i have the center pin from 7815 going to pin 5 of the opto

the load is resistive and capactive componet for a medical sterilizer


the 555 has a fully function square wave generator with bridge 3 1000 uf caps 7805 regulator .01 uf cap a 100k pot a .01 uf cap and a 1k resistor

 

Also, pin 5 of the opto must be connected to ground and pin 8 to 15V. You have them in reverse. If this is a schematic false you are lucky otherwise you will need a new opto. What is more run the 555 on 15V as Beenthere suggested as not to use another voltage regulator for 5V.

 

i forgot to add the rectifier for the 7815

i have the center pin from 7815 going to pin 5 of the opto

the load is resistive and capactive componet for a medical sterilizer


the 555 has a fully function square wave generator with bridge 3 1000 uf caps 7805 regulator .01 uf cap a 100k pot a .01 uf cap and a 1k resistor

If the load is resistive what is the purpose of the two inductors and the diode in the diagram?

 

I wish you finally achieve it. If you need more help come back here

 

mik3 dose it look like the way im trying to do it should work or am i wasting my time also the inductors in the have some piezo vibrating material on them like ultrasonic

and do you have any suggestion on how i could make the igbt force the chopped up half wave dc into the inductor to do this

 

With the circuit you have now, if it works properly, the load (inductors, resistor, etc) will see the chopped signal across it. If you measure the voltage on the collector of the IGBT with an oscilloscope you will see the chopped voltage.

 

i took every ones suggestion and made a new schematic is it correct or is their something i should change and what would be the approximate value of the resistor from pin 3 of 555 to pin 2 of opto and dose this change the value of the resistor to the igbt

 

This is better than before.
Use a 900 ohm resistor from the output of the 555 to the opto.
Use a 10 ohm resistor from the output of the opto to the IGBT.
Connect a 10K resistor between the gate and emitter of the IGBT in case the opto fails the IGBT will turn off for sure.
Connect a fast diode which has an ampere rating the same as the ampere the load draws with its anode connected to the collector.

 

mik3 i have the hole circuit built to the schematic i put 900 ohms on the 555 out put to the opto and it wont turn on i measured voltage at the opto from the 555 and is about 7 volts after the resistor i checked no voltage coming out opto should i lower or raise the resistor value i only have 3 optos left and cant really try to experiment myself



sould the 10k resistor between emitter and gate be 5watt

 

Flip the positions of the 100L and the 1K resistor on the 555. For the 10K just use 1W.

 

mik3 i flipped the 100k and 1 like you said i now have a squarewave comming out of the opto output but their is no measurable voltage meter says 0 but scope shows wave on .1 volt setting should i change the resistor from 555 to opto so it can fully latch open if so how much