Need Transistor to relay help ASAP

[Slobin3d]

LOL.

Well I did V-2 version, and this is what I got. My 3 is series was bad, cooked a resister or something, I was only getting 1.6k across all 3. So I replaced them with 2 3.3k resistors that should do the same job as 3 2.2K's? I'm getting 16v across the pair, and across the single resister

Problem 1 I'm having. I'm getting 36v to my 24v hot, (charged 12v batteries are at 18v each)

#2 I'm getting voltage at the relay output. 20 at neutral 24 at full throttle and 18v at full reverse

#3 Even at 24v the circuit's not putting out enough amperage to activate the relay


I'm stumped

 

[Slobin3d]

my thought is that maybe my transistor is bad? I'm reading 0 continuity between E and C in either direction, and continuity between B and C only

 

[CocaCola]

I suspect you have made multiple errors somewhere in the design when you wired it up, as little you said make any logical sense That or the original data you supplied to design the circuit was in error... You did pay close attention to the 'dots' on the diagram that indicated connection points vs two lines just crossing each other didn't you?

I really don't have the time to trouble shoot right now, my days are chunked up into little 5 minute blocks between a toddler and newborn, makes for a scrambled mind until they are both down for the night

 

[Slobin3d]

I suspect you have made multiple errors somewhere in the design when you wired it up, as little you said make any logical sense That or the original data you supplied to design the circuit was in error... You did pay close attention to the 'dots' on the diagram that indicated connection points vs two lines just crossing each other didn't you?

I really don't have the time to trouble shoot right now, my days are chunked up into little 5 minute blocks between a toddler and newborn, makes for a scrambled mind until they are both down for the night

I did notice the cross points vs connections. I will double check again. I had to rewire it this morning due to the bad resistors in the 6.6k bundle, I may have missed something

 

[CocaCola]

I had to rewire it this morning due to the bad resistors in the 6.6k bundle, I may have missed something

See that is the thing, it's very unlikely the resistors were bad, and if they where they usually stop conducting altogether... I have no idea how you got 1.6K from them, the best quick calculation I could come up with was that you put two in series and one in parallel that would result in about 1.46K...

 

[Slobin3d]

See that is the thing, it's very unlikely the resistors were bad, and if they where they usually stop conducting altogether... I have no idea how you got 1.6K from them, the best quick calculation I could come up with was that you put two in series and one in parallel that would result in about 1.46K...

I don't know either. i pulled them from the board and tested them separately and was still only showing 1.6K each, and 1.6K over the strand. i'm guessing they got cooked, but I'm now showing proper resistance through the paired 3.3k's either way

 

[CocaCola]

Again you are only further confusing me,,, If each resistor 2.2K measured 1,6k (it shouldn't) and you put them in series you would get 4.8k not the original 1.6k... This to me indicated one of two things, you meter is broke or you are not properly measuring them...

Same with the batteries, a standard 12 volt battery will not put out 18 volts, it will generally be in the 14 volt range fully charged but not 18...

In short the numbers you are tossing up make no sense, and a total rewind to the start is almost certainly in order...

 

[Slobin3d]

The 2.2 resistor makes no sense to me either. But they aren't there any more so it's kind of a non issue anymore lol

As far as the batteries, they are 12v Lead acid batteries in series. But for some reason at the board I'm getting 36V In my rush to get this thing going I did not check that the batteries are actually at 12v, I assume that they are heavily overcharged, resulting in the 36v that i'm seeing.

maybe at lunch, I'll run back to the shop and grab the board I made and trace out exactly how I wired it and maybe it will make more sense

 

[CocaCola]

The 2.2 resistor makes no sense to me either. But they aren't there any more so it's kind of a non issue anymore lol

It's still a concern of mine because if the same issue it causing you to toss up other incorrect data it's only going to continue to cause problems... The chance of the resistors being faulty is slim and even if they where when you put them in series the resistance would increase not remain steady... As I said this leads me to believe one of two things, you are improperly measuring them or the meter is faulty, either or both of these issues will continue to aggravate coming to a solution...

As far as the batteries, they are 12v Lead acid batteries in series.

How many? Just two?

But for some reason at the board I'm getting 36V

Or your meter is faulty, or you are measuring incorrectly, or.... See this is why I say the point of the resistor not measuring properly still comes into play and is not a moot point? You are getting all sorts of measurements that make no sense, time to figure out why before you continue to run forward blindly...

In my rush to get this thing going I did not check that the batteries are actually at 12v, I assume that they are heavily overcharged, resulting in the 36v that i'm seeing.

Right back to page one, it doesn't work like that... If you are truly getting 18v out of the batteries you are causing them damage... If you are charging them this high you risk an explosion! Time to rewind and figure things out...

 

[BobK]

I looked at the schematic I posted and the dots vs crossing lines are really hard to see. There are very obvious dots where components connect, but when lines cross and connect there is just a tiny grey square. Anyway, let's make sure you are reading the schematic correctly.

The ONLY non connecting crossing point is the line from the throttle input to pin 5. Everywhere else you see lines crossing they should be connected. In particular there should be 3 things connected to V+ and 3 things connected to ground. Is this the way you interpreted it?

Bob

 

[CocaCola]

For clarification I have uploaded another slightly modified image of Bob's schematic to clarify connections...

 

[Slobin3d]

Went and grabbed the board, and my multimeter. Turns out it is bad. I have a cheapo spare that seems to be functioning, ill report back in a few my findings

 

[BobK]

For clarification I have uploaded another slightly modified image of Bob's schematic to clarify connections...

Thanks, it is hard to miss those dots!

Bob

 

[Slobin3d]

So this much I have so far, it is 24v and my signal is 2.5V not 5, and Forward throttle starts at 1.25V the Ohm readings are all over the place on my old meter. I'm going through everything with my spare meter in a lil bit. I'm at work

Edit: My spare meter is reading the resistors correctly so it's going away now. lol

 

[Slobin3d]

I drew out how I have it connected as it sits on the board. Hope you can read it

 

[CocaCola]

To be blunt what a mess, that is nothing like the diagram Bob posted...

 

[Slobin3d]

lack of sleep may have been a factor. lol

 

[BobK]

These connections bear little resemblance to the schematic I posted.

The emitter is supposed to be connect to ground and only to ground. You have it connected to the relay and to the minus input of the comparator.

The base is supposed to connect to the 3.3K resistor as well as the output.

The collector is supposed to connect to one of the relay leads and to the anode of the diode. You have it connected to a 2.2K resistor.

It appears that, among other things, you have reversed the emitter and collector. On the transistor symbol, the emitter is the lead with the arrow in it.

I think you also missed the connecting dots which were hard to see in my original schematic.

Please look at C.C.'s latest schematic with the connections very explict and re-wire from scratch.

A good way to do the wiring is to print a copy of the schematic and do one wire at a time, crossing it off as you make the connection. When everything is crossed off you are done. Then you should use a continuity tester to check each connection on the circuit and mark it again in the schematic.


Bob

 

[CocaCola]

I have to asked do you know how to read a schematic? There is so much wrong with that, that you really need to rewind to that start and start over...

 

[BobK]

But don't be too discouraged, at least you didn't let the smoke out of anything yet, (though there could be damage anyway).

Bob