Those type of pots tend to have dead spots on the extreme ends of travel - chances are you hit one of those and caused the board to generate more voltage than it is capable of. They are not a good replacement pot - the 10 turn type that is in there is a precision pot. If the smoke you let out was only from the diode, you mayh be able to fix it. Or you also may have fried the LM2577 chip, too. I would doubt that the caps are damaged or bad, as they will either puff up or explode. And the pot is a 10kΩ pot.
- Status
Those type of pots tend to have dead spots on the extreme ends of travel - chances are you hit one of those and caused the board to generate more voltage than it is capable of. They are not a good replacement pot - the 10 turn type that is in there is a precision pot. If the smoke you let out was only from the diode, you mayh be able to fix it. Or you also may have fried the LM2577 chip, too. I would doubt that the caps are damaged or bad, as they will either puff up or explode. And the pot is a 10kΩ pot.
Thanks. So correct value pot but not a good one. I tried replacing the diode with a ss36 I found on the speed controller but it didn't make a difference. I'm thinking its the 101 square (inductor I think??) or the lm chip itself. Not sure if there is much point messing with it as I have no idea how to trouble shoot so I just blindly replacing parts.
Chances are it is not the inductor, they are mearly wire wrapped around a core. Most likely the chip is blown. Not worth replacing, IMHO, as the price of components is probably more than a new board!
Agreed....I will just leave the pot on my good one for now and probably order a five pack from china and maybe a 60v (never know when it will come in handy
)
lol. That has been my side project (education) for the last two weeks. The wife is asking why I have all these disposable camera parts laying around.
BTW. Breaktru has some good tutorials on his site.
Got some time to work on my LM box. I hooked up my second display meter to the cap and like I figured it drained the cap.
But what I would really like to do is add an led that lights when the cap is charged. Any suggestions? I figure it will need to be some kind of relay that senses voltage and allows power from a separate source to power the led....????
But what I would really like to do is add an led that lights when the cap is charged. Any suggestions? I figure it will need to be some kind of relay that senses voltage and allows power from a separate source to power the led....????
I actually just thought of a way easier solution....wire the volt meter sense lead into a switch so it can be switched between the LM output and cap. Not that it is really needed, I would just like to know if the cap is charged.
gsa,
Are you going to post your how-to guide for building one of these in here or in another thread?? I have all of my stuff just waiting for some guidance.
Steve
Are you going to post your how-to guide for building one of these in here or in another thread?? I have all of my stuff just waiting for some guidance.
Steve
The proper way to do that would be to use an op-amp to sense the voltage of the cap - its high impedance would not drain the cap and would not be fed by the cap, rather by the LM....
Radio shack has this LM741CN....any quick tips for wiring it?
Having a hard time....if 7 & 4 are supply and 3 is cap voltage it looks like it will output the cap voltage
Last edited:
I'll take a look at the specs sheet and see what I can come up with - I use the LM339 in most my projects, its a quad op-amp chip. A google search for op-amp voltage comparators will probably turn up a number of useful circuit ideas. Basically, you feed the output through a resistor to one input from the cap and the output of the board through a resistor to the other input - when they match you turn on the op-amp. This is a simple explaination - theres a little more to know than that.
Just a note - you will have to put a separate voltage regualator of say 12V or 15V to power the chip. Like an LM7812 or LM7815. These can be fed directly from the output of the LM2577 board.
My voltage regulator of choice is the LM317 - it is an adjustable regulator from about 1.5V - 37V. It requires 2 resistors to select the voltage and can be variable if one of the resistors is a pot. Drawback is the input V must be higher than output V by about 1.5V. It is in no way a boost regulator - a simple buck - eroo!
I am going to put it here. I am still waiting on my lm2577 board, first one came quickly but the USPS is taking their sweet time with the second....
Radio shack has this LM741CN....any quick tips for wiring it?
Having a hard time....if 7 & 4 are supply and 3 is cap voltage it looks like it will output the cap voltage
Not how it works... Cap would go to the - input. Through a voltage divider, the board's output voltage to the + input. When the - input is higher than the + input, the output goes to what ever the supply on 7 and 4 is. The voltage on 4 specifies negative, but this can be ground in our application. A voltage divider should be used for the cap also - with a pot to dial in the desired turn on point. It should be set so that it will turn on at slightly less than full charge; otherwise it will turn back off after the cap naturally loses some voltage due to internal leakage.
Last edited:
Kinda seems more complicated than it is worth...for me anyway....I was thinking it could be set to turn on the led at around 5-12v
If using a 12v supply to the LM could that source go to both pin 7 & 3 and cap go to pin 2....so it would output 12v when the cap was higher than 12v
Double barrel 4700's for when 18 gauge is all the rave
nice looking setup man
I was also thinking about doing one with the caps on the outside for easy switching and it kind of gives it a retro look like an old tube setup, all you need now is an analog voltage display. what where those connectors you used called?- Status
Similar threads
