manoj.patil.1974
New Member
Hi,
Thanks for the response guys !
This time, I purchased BT138 and BT139.
The dimmer now works perfectly fine with a 470K pot. Adding the hysterisis circuit results into a visibily gradual dimming as compared to sudden pop up of the bulb when its not connected.
The BT138 had smoke for a 1000W heater coil (new load), but then it did not get damaged. It works fine for the 100W bulb again. The tab appears black and plastic like..
The BT139 800E works perfectly fine for a 1500w heater coil. The heatsink gets really hot so looks like I have to work a bit more on the snubber circuit and heatsink calculations. Any good tutorial/note that can help me with best practices ?
I did not want to give up on the BTA16 though, so I brought a MJE13001 high voltage transistor. The diac was connected to the MJE base via 4.7K resistor. Collector to the main line via 600ohms and the emitter directly to the gate of BTA16. My attempt here was kind-of to amplify the gate drive current, but the bulb was Full on for any value of resistor in the RC network.... looks like I have to relook at the calculations and also there may be more things happening in this AC network and amplification may not be as simple as adding a transistor.
Thanks for the response guys !
This time, I purchased BT138 and BT139.
The dimmer now works perfectly fine with a 470K pot. Adding the hysterisis circuit results into a visibily gradual dimming as compared to sudden pop up of the bulb when its not connected.
The BT138 had smoke for a 1000W heater coil (new load), but then it did not get damaged. It works fine for the 100W bulb again. The tab appears black and plastic like..
The BT139 800E works perfectly fine for a 1500w heater coil. The heatsink gets really hot so looks like I have to work a bit more on the snubber circuit and heatsink calculations. Any good tutorial/note that can help me with best practices ?
I did not want to give up on the BTA16 though, so I brought a MJE13001 high voltage transistor. The diac was connected to the MJE base via 4.7K resistor. Collector to the main line via 600ohms and the emitter directly to the gate of BTA16. My attempt here was kind-of to amplify the gate drive current, but the bulb was Full on for any value of resistor in the RC network.... looks like I have to relook at the calculations and also there may be more things happening in this AC network and amplification may not be as simple as adding a transistor.