Tweet
After a long time reading and lurking the time has come to post a question.
I have been working on my Surf PI 1.2 project for quite a while now but, as with everything I start, it all seems to take a long time.
Although I have had many years experience in electronics, mainly hobby but some professionally, I got a bit lazy with this project and bought a finished board from Turkey and set about making a coil and waterproof case to do a bit of beach hunting. Everything seemed to be working well until I began fitting the works into the case made from 50mm diam PVC water pipe. When I pushed the end caps into place it stopped working and was still intermittent after removing them again and soon died altogether.
Anyway, it turns out that the 7555 was no longer producing pulses and the mosfet was turned on and getting quite warm, as were the 2 100R resistors in series with Q2 and the damping resistor, even without the coil connected. I figured the 7555 was the culprit and , out of curiosity replaced it with a 555, whereupon everything was back working again and I had not cooked the transistors being driven by it.
This got me wondering which timer was better to use, the CMOS or standard version. I feel sure I have read some discussion on this here but could not find it again.
I also looked up the datasheets to check on supply voltages and both are safely within what my 3 x 3.7V lithium rechargeable pack is supplying.
So, my question is, should I stick with the 555 as per the circuit diagram or go back to a 7555 as was on the board originally?
I have been working on my Surf PI 1.2 project for quite a while now but, as with everything I start, it all seems to take a long time.
Although I have had many years experience in electronics, mainly hobby but some professionally, I got a bit lazy with this project and bought a finished board from Turkey and set about making a coil and waterproof case to do a bit of beach hunting. Everything seemed to be working well until I began fitting the works into the case made from 50mm diam PVC water pipe. When I pushed the end caps into place it stopped working and was still intermittent after removing them again and soon died altogether.
Anyway, it turns out that the 7555 was no longer producing pulses and the mosfet was turned on and getting quite warm, as were the 2 100R resistors in series with Q2 and the damping resistor, even without the coil connected. I figured the 7555 was the culprit and , out of curiosity replaced it with a 555, whereupon everything was back working again and I had not cooked the transistors being driven by it.
This got me wondering which timer was better to use, the CMOS or standard version. I feel sure I have read some discussion on this here but could not find it again.
I also looked up the datasheets to check on supply voltages and both are safely within what my 3 x 3.7V lithium rechargeable pack is supplying.
So, my question is, should I stick with the 555 as per the circuit diagram or go back to a 7555 as was on the board originally?
Comment