RLC project - Page 1
Forum section: electronics / projects

author: donthack22
author_rank: Contributor
timestamp: March 23, 2019, 05:49:38 pm
content: Hello guys, i am trying to do RLC1 project from this website. I got everything done on my perfoboard, but when i connect the 9v source i cand get 5V and -5v. I tried the to the first part of the circuit that uses those transistors on a breadboard and it seems i cannot obtain +5v using this schematic. I have done everything like in the schematic, i checked a lot of time. So i dont know what am i doing wrong. If anyone has some ideas i would be very grateful.

author: kripton2035
author_rank: Super Contributor
timestamp: March 23, 2019, 07:14:27 pm
content: which website ?

author: donthack22
author_rank: Contributor
timestamp: March 23, 2019, 08:48:52 pm
content: http://kripton2035.free.fr/LCR%20meters/lcr1-go-russian.htmlthis website, your website. Sorry, i dont know why i didnt link it the first time.

author: Arznei
author_rank: Contributor
timestamp: March 23, 2019, 09:16:16 pm
content: What did you connect R34 (where it says "PWR ON RC7") to? If you left it floating and the capacitor C26 still has charge your circuit will not work. You can try to connect "PWR ON RC7" to the +9V input to check if that is the issue. Also make sure the Diode D3 is inserted in the correct orientation.Other than that I'm afraid I cannot help you without some more information. Like what voltages do you measure where the +5 and -5V are supposed to be? Do you measure 9V at the input of the 7805? Are you sure there are not shorts or missing connections? Maybe a photo could help and so on.

author: donthack22
author_rank: Contributor
timestamp: March 23, 2019, 09:33:31 pm
content: I had it connected to the RC7 pin of the microcontroller. I tried to connect it to the 9 V and it doesnt work, but if i connect the base of the bc548 tot he ground it works. Also if i put a wire between R34 pins it also works. But i cant understand why. And it also works if i get the PWR ON end to the barrel connector ground. The diode is in the right direction and i measure around 5v at the entry of 7805 if i dont do one of the things i listed. If i do one of them there are 5 V

author: donthack22
author_rank: Contributor
timestamp: March 23, 2019, 09:45:42 pm
content: I could make some photos if you like, but i didnt work too nicely and i am afraid you wont understand what is going on, cuz i got a lot of wires and i am a little ashamed too

author: Arznei
author_rank: Contributor
timestamp: March 23, 2019, 10:00:05 pm
content: Well that's good news, now you know most of your circuit is correct and where the problem is. Are you sure you have the pinout of the BC548 correct? It should actually *not* work when connecting the base of it to ground, as far as I understand. Can you try pulling R37 to ground? From my understanding your circuit should then work. I am a bit tired though, so maybe I'm just confused here.Also, I did not know you already have the PIC installed. Please make sure to *not* connect PIN RC7 of the PIC to the +9V when changing things around.

author: kripton2035
author_rank: Super Contributor
timestamp: March 23, 2019, 10:02:12 pm
content: what voltage is at the + side of C21 ?

author: donthack22
author_rank: Contributor
timestamp: March 23, 2019, 10:08:30 pm
content: Yes, it works if I do what you sugested. But can you explain to me tomorrow, cuz i dont want to take your time now if you are tired, how you figured it out and if i should leave it like this, without the C26. And i also got a few other problems, but if you want and if you would like to help me we can talk tomorrow

author: donthack22
author_rank: Contributor
timestamp: March 23, 2019, 10:10:11 pm
content: If i dont do what Arznei suggested there are 3.6 V, if i do what he suggested there are 8.6V at C21 +

author: kripton2035
author_rank: Super Contributor
timestamp: March 23, 2019, 10:43:18 pm
content: didn't you reverse the 78L05 ?

author: donthack22
author_rank: Contributor
timestamp: March 23, 2019, 10:51:30 pm
content: I am pretty sure that i didnt. Lets see, if the straight face its towards me the first pin should be output, the second one should be ground and the third one should be the input, right?

author: kripton2035
author_rank: Super Contributor
timestamp: March 24, 2019, 06:10:21 am
content: 8.6V at C21+ seems ok. what do you have at the output of the 78L05 ( or C17+) ?

author: donthack22
author_rank: Contributor
timestamp: March 24, 2019, 09:10:51 am
content: I got 5V, but again i have to mention that i got 5 V only if I do what Arznei told me. If i dont i get like 2 V. My issue now is that even if i got 5V, i cant get -5v from ICL7660, io get only around -3.40V. I know for sure that before i connected all integrated circuits ( tl082, ad620, 4053) i got -5V and i dont know what may be the problem. I first thought that maybe ICL 7660 doesnt provide enough current, but this circuits doesnt require a lot of current.

author: kripton2035
author_rank: Super Contributor
timestamp: April 07, 2019, 08:57:32 am
content: did you try with another ICL7660 ? is it an original one or a "china exported" one ?

author: donthack22
author_rank: Contributor
timestamp: April 07, 2019, 10:33:59 am
content: It s a chinese one indeed. I will try with an original one.