friggin chargers!

[BoatDoc]

alright! now i'm upset! i was chargin' up my recievers/transmitters, and my supply smoked itself...again! i use a hanger 9 charger. the charger is good, but the hanger 9 12v power supply sucks. basically, it's just a transformer to get 12v power from a 120v wall socket. now that i've burned two of them, i need ideas for a new one. this one will go back to the LHS for a refund, but i need something different, that won't burn up.

[Hydro Junkie]

Radio Shack......I built a 12 volt DC power supply using an 18VAC secondary transformer, a bridge rectifier and a capacitor. The output was 12.726 volts at about three amps. Just for safety, I included a fuse in the negative output line to keep from melting any of the components. If you need more amperage, build two or three and rig them in parallel. Make sure you are using a heavy duty cord if you run more than one of them off one power cord. You might also want to build them with a printed circuit board, as it prevents the use of wiring except input and outputs. I would also recommend a case of some sort to eliminate the chance of touching a hot wire or contact :)

[BoatDoc]

that's a good idea. i think i'll look into it. maybe with a built in cooling fan?? maybe i'll build 2 so i can have a seperate power supply for charging my 6 cell packs too. could you post more info on that, like part #'s or something. if i know which parts to use i can build it. if you don't know the part #'s, how about a few specs.

[Hydro Junkie]

The parts I used are transformer number 273-1515, a standard bridge rectifier, and a 10 microfarad can style capacitor. I was wrong about the output, as the transformer is rated at 18VAC at two amps on the secondary side. How I wired this up is:
1. power cord to transformer primary contacts
2. transformer secondary contacts to AC inputs on bridge rectifier
3. DC side of bridge rectifier to outputs through inline fuse on negative out
4. capacitor installed between output leads

Sounds too simple, doesn't it. Now to explain how this works for those not familiar with electrical circuits. Simply put, power comes into the primary side of the transformer at 120 volts AC. The transformer reduces the voltage down to 18 volts AC in the secondary(and no, I'm not going to explain how as it would take all day :D). The 18 volts is converted by the bridge rectifier to a pulsing 12+ volts DC at it's output. The capacitor smooths out the pulses to give a fairly constant 12 to 13 volts DC.
When you buy your parts, make sure the rectifier and capacitor are rated at higher than 120 VAC. Just in case something happens to the transformer, the rest of the parts will be able to handle it without burning up. If you want to get fancy, you can add a case, an on/off switch, voltage and amperage meters, and even a power on indicator light. If you put it in a case, I would recommend a panel mounted fuse holder instead of the inline, as well as output jacks either labeled, color coded or set up in some way to prevent crossing the outputs. That's all there is to it. I would also recommend a circuit board kit and spacers to raise the board off of the bottom of the case.

[BoatDoc]

just how stable is it?? also, you said the transformer puts out 18v, does the bridge rectifier bring it the rest of the way down to 12? i think i need 5 amp output on it too. i also have an mpi charger that'll i'll be using for my 6-cell packs in my blizzard. it says it needs a constant 12v, no "waves". so i need to get as stable of a source as i can.

[scottericsonon]

I built a dual power supply to run my 1/32 slot-car track almost EXACTLY the same way

i can dig up the schematic if youre interested

mines GREAT we can run cars all day without it getting hot

scott

[Hydro Junkie]

Now I feel better, an electrical engineer does it the same way :D The output will average out to 12.726 VDC. When you convert AC to DC, to get the equal level, you multiply the AC voltage by .707. To go from DC to AC, multiply by 1.414. The bridge rectifier doesn't lower the voltage, it converts it to a pulsating DC. The output wave looks like a bunny hopping across the screen till it gets to the capacitor. The capacitor acts like a quick charging/discharging battery. As the voltage gets higher, the capacitor charges, just like a battery. As the voltage drops, the capacitor discharges, holding the voltage at the output to a constant level. There is probably less than a .2 VDC variance in the output :) I've used my setup to power DC radios, electric pumps and several other things without a problem. If you need more power, you could build two circuits and wire them in parallel. You would need to make sure you have both negative sides come together to keep from burning up the transformers by hooking positive to negative. You can set it up where both rectifiers dump into one capacitor, though I would recommend a capacitor of at least 25 to 50 microfarads instead of the 10. What do you think Scott?

Hold The Bus!!!!!!! Just called Radio Shack and learned they only carry a one amp transformer with an 18 volt secondary :mad: You will have to look around at some of the electrical supply houses and battery shops to find one bigger. Otherwise, you will need to buy FIVE of the one amp types and run them in parallel :(

[BoatDoc]

it's lookin' like i'm going to be making a trip to radio shack. watch out hydro...i'll be charging electric boats with it too (gasp!!).

[Hydro Junkie]

You may want to do some calling around first to see if you can find a 5 amp transformer with an 18 volt secondary :(

[BoatDoc]

crap...it just got complicated didn't it?

[Hydro Junkie]

I hope not. You might call Radio Shack and see if they could refer you to someplace that might sell a transformer that size, or larger. As long as the secondary is 18 volts, you will get the 12VDC out of the rectifier, no matter how many amps the transformer is rated at. The other thing you need to remember is the amperage rating is the max the transformer can handle, not a fixed amount. You could use a 20 amp transformer in a circuit that only needs one amp or less, but you can't use a one amp transformer in a circuit that needs more than one amp without frying the transformer.

[FlyerCAN]

the bridge rectifyer must have a zenir diode built in to bring the voltage down to 12V.
???

[Hydro Junkie]

Nope, the rectifier is actually FOUR DIODES connected together in such a way that when the AC enters the rectifier, the current can only go one way. To give you an idea how this works, we will use one way check valves for the diodes. If you arrange the check valves in a square, with all the valves set with water flow going to the right, all water will be going to the right. If you put two water supply lines between the valves, the water will try to go through all four valves. As water cannot flow through the left side check valves, it must go right, through the right check valves. If you alternate the water on and off through the supply lines, you get the effect of AC current. Water can return through the left side check valves, to be sucked out through the supply line not pumping water in. As the water flow alternates between the two supply lines, the pressure pulsates going out. By running the water through an elastic tube, the flow rate and pressure go from pulsing to constant, resulting in a 30% apparent drop in voltage, though the volume of water out is the same.
Hope this makes some sense :)

[bufferoo]

I've often used surplus computer power supplies in the past. You've got VERY clean 5v & 12v supplies there. I used to power a 80 W car amp off the 12v side. Worked great and never had a failure. Usually the 12v is a 5 amp supply on a 250 w supply. I've seen them down to 3 amp but that's rare and usually on an older AT supply. A good 300 watt ATX supply should give you all the juice you need.

Bufferoo

[BoatDoc]

thanks bufferoo, i'll look into that too. the manual on the charger is very specific about the input power. and that sounds like the best way to go, outside of using my 12v battery. the only reason i don't like using the battery is that i need to charge it and the boats at the same time!

[scottericsonon]

WHOA
im not an electrical engineer

whever did you hear that????

i build dump trucks im a welder/fabricator/hydraulic engineer

sounds to me as if hydro has a better handle on electrics than i do

computer power supply WILL work


if you need a SERIOUS supply try this one

Parts List

R1 1.5K ¼ Watt Resistor (optional, tie pins 6 & 5 of IC1 together if not used.)
R2,R3 0.1 Ohm 10 Watt Resistor (Tech America 900-1002)
R4 270 Ohm ¼ Watt Resistor
R5 680 Ohm ¼ Watt Resistor
R6,R7 0.15 Ohm 10 Watt Resistor (Tech America 900-1006)
R8 2.7K ¼ Watt Resistor
R9 1K Trimmer Potentiometer (RS271-280)
R10 3.3K ¼ Watt Resistor
C1,C2,C3,C4 4700 Microfarad Electrolytic Capacitor 35 Volt (observe polarity)
C5 100 Picofarad Ceramic Disk Capacitor
C6 1000 Microfarad Electrolytic Capacitor 25 Volt (observe polarity)
IC1 LM723 (RS276-1740) Voltage Regulator IC. Socket is recommended.
Q1 TIP3055T (RS276-2020) NPN Transistor (TO-220 Heat Sink Required)
Q2,Q3 2N3055 (RS276-2041) NPN Transistor (Large TO-3 Heat Sink Required)
S1 Any SPST Toggle Switch
F1 3 Amp Fast Blow Fuse
D1-D4 Full Wave Bridge Rectifier (RS276-1185)
T1 18 Volt, 10 Amp Transformer Hammond #165S18 (Digi-Key HM538-ND)

[scottericsonon]

forgot schematic

[Hydro Junkie]

Sorry Scott, got you and someone over in the beginners area mixed up. I guess it was how much R/C knowledge that you have. That is quite a schematic you have there :eek: Was I reading it right, at 13.8 VDC out? :cool: I"ll have to do some serious studying to see what all is in it, as well as how to make a circuit board for it. Where did you find this, anyway?

Added Note: Unless you are a professional soldering tech, THE RECOMMENDED SOCKET FOR IC 1 IS REQUIRED!!!!!!!! If you try to hand solder an integrated circuit like that, more aften than not, you will either burn it up with the soldering iron or short it across two or more legs. Using a socket will let you make mistakes, to a point, without burning it up. A HEAT SINK IS ALSO REQUIRED FOR THE TRANSISTERS Q1, 2 AND 3 for the same reason.

[BoatDoc]

that schematic is a little too much for me. i'm a hammer mechanic!!! good thing i work with aircraft electricians...i'll see if one 'em will help me. i love building stuff, but if doesn't involve hammers and large power tools i get lost.

[Hydro Junkie]

Now Doc, you sound like a Navy Airframe Mechanic :eek: It's not really that complicated :D hehehe

Added note: I would add a cooling fan with a heat activated switch beween the plug and S1 on one side and between the plug and the transformer on the other. Those transisters and resisters will get VERY HOT without one, especially when putting out 10 amps

[BoatDoc]

i'm an army powertrain mechanic!!! i get to hit blackhawks and apaches with hammers. i like hammers. i like hammers a lot. and i like to hit things with them even more!!!! like i say to the airframe guys everyday..."if you ain't powertrain, you ain't #$#&"

[Hydro Junkie]

Calm down Doc, just having a little fun :D Besides, I like hammers too :D I just don't get to hit multimillion dollar whirlybirds.........I mean attack choppers :D hehehe

[BoatDoc]

there's something really satisfying about laying into a blackhawk with a BFH. but like i said, i'll probably show that diagram to one of the electricians and have them help me out. or i'll go with the PC power supply idea. i'm just sick of burning up power supplies for no apparent reason. mmmm...maybe next time i'll just knock it with a hammer :D

[Hydro Junkie]

There are three things electronics DO NOT LIKE; water, excess heat, and a BFH!!!!!!!!!!! Or should I make it four and include ARMY MECHS WITH BFH's? :D Trust me on this one, electronics can infuriate you more than not having your BFH or your Apache to hit with it. After spending 3 years working on EA6B Prowlers, which must be the world's most unfriendly to electricians aircraft, I lost track of how often I wanted a BBFH to beat the $#(^ out of those things, and the people who designed it :D

[scottericsonon]

N/P hydro

yes it is 13.8 VDC @ 10 AMPS out

i personally havent built this one yet but it looks pretty beefy

i built two non regulated supplies for my kids slot car track

i dont think they will push enuff amps for a charger tho i can get about 5-5 1/2 out of them but thats it due to them getting REAL hot

slot cars only draw 1-2 even my ballistically fast drag cars loaded with magnets

THIS is the supply i built MUCHO simpleir

T1 - Transformer : 12 volt secondary, 115 volt primary, 3 amp rating
C1 - capacitor : 15,000 microfarad polarized electrolytic 25 volt rating (or larger)
S1 - switch : miniature/subminiature toggle switch single pole, double or single throw, 3 amp
D1 - full wave rectifier bridge : 25 amp 50 PIV (peak inverse volts) aluminum case preferred
Fuse : 2 to 3 amp rating (enclosed unit recommended)
Circuit Breaker : 5 amp rating (fuse holder and 5 amp fuse can be used)
Enclosure : Aluminum 2 part case (do not use plastic)
Power cord : 2 wire (polarized) or 3 wire (3 wire recommended)
Rubber grommets (2) : to isolate incoming / outgoing wiring from enclosure
Rubber feet (3/4) : stick on recommended (optional)
Banana Plugs - red/black (optional)
Wire : 14 gage minimum recommended

[Hydro Junkie]

Looks like mine, except I put a single fuse in the output. I do need some clarification though. Is the 12 volts at the transformer secondary or at the output of the bridge rectifier? If it's at the transformer, you have an 8.5VDC output from the bridge rectifier, instead of 12VDC.

I was just thinking :eek: The big 10 amp unit might be strong enough to run my 12VDC starter when I start my boats :cool: The only problem is getting the AC down to the pits, and that's only if AC is available :)

[scottericsonon]

actually hydro we get about 16VDC out of that one but as i said its non-regulated so that drops under load

thats why u need 2 for slot cars ....one for each lane

otherwise if someone crashes the other car gets ALL the juice and acts like you hit the nitrous button LOL

10 AMP might run a starter

but why dont you do what i did for my starter box for the NTC3?

i bought a gel-cell motorcycle battery and have it strapped int a craftsman tool box

i charge it between uses with a cheap motorcycle battery tender trickle charger

best thing about it is i can fit all my crap except car and fuel in the toolbox

starer box tools some glowplugs etc etc

scott

[Hydro Junkie]

Had a wet cell battery. Unfortunately, it's so old now that it won't even take a charge. I think I'll hold off on getting something till I get one of the boats ready to get wet. You know how hard it is to wait :( IT'S DRIVING ME CRAZZZZZZYYYYYYYYYY :D

[BoatDoc]

hey HYDRO!!!!! if you're having trouble finishing your boats...get a BLIZZARD!!! you could have it built in a week or less. or you could get a firefighter nitro 'rigger, and have it built just as fast!!! how does 70 mph sound??

[Hydro Junkie]

HEY DOC.....IF IT AIN'T SCALE AND DOES'NT DO 60, IT AIN'T IN MY HOUSE!!!!!!!!!!! I could have said something else, but I thought I'd better keep it clean :D It's not that I have trouble finishing them, it's that I have to wait till the Miss Madison/Oh Boy Oberto shop sends me info or comes to Seattle for SEAFAIR in August. The waiting can really be a drag. Kinda like having to wait to bash the crap out of a Blackhawk. Know what I mean? Speaking of waiting, went down to Miss Budweiser shop today :D Spent almost two hours getting specs on one of the trailers and another 45 minutes talking with Dave the Driver :) Not a happy camper, since Budweiser is pulling all of their money out of Unlimited Hydroplane Racing :mad: It will be the last year of the Miss Budweiser and probably Dave's last in an unlimited boat, unless something drastic happens to change the minds of the Budweiser execs :eek: Needless to say, I wasn't too happy when I left the shop either :(

[BoatDoc]

i heard about bud pulling the sponsership...and i think they are making a BIG mistake. Miss Bud is the fastest unlimited boat, and has countless records and...anyway...if you're "bad to the bone" why don't you build a good 'rigger like a matrix on 24 cells or a .21 firefighter. i know they're not scale...but they are FAST!!!!!! i've heard the matrix will top 90 without blinking an eye! the firefighter is good for about 70 mph. so why don't you join the rest of us and drive some REALLY fast boats :D

[Hydro Junkie]

Let me count the reasons:
1. I've seen scale boats do over 80 on a measured 1/16th mile

2. I've seen scale boats do over 70 on an oval

3. I have one sport 40, three 1/8th scale and two 1/6th scale boats under construction :cool:

4. Scale boats look so realistic going through a corner with their dual roostertails and scale paint schemes :cool:

5. A nitro boat will run at full throttle as long as if has fuel in the tank, an electric starts to slow at around 3/4 charge

6. Few electrics are bigger than my sport 40 and none are as big as my scale boats

7. I have the starter and glow igniter, not a charger

8. The significant other says no more till the rest are finished. That says it all, doesn't it :)

[scottericsonon]

number 8 there well thats what it all biols down to

id have a veritble R/C FLEET if it wasnt for that

scott

[BoatDoc]

calm down hydro! (mmm...sound familiar?) :) i don't have a significant other to limit my hobbies...just an army paycheck!! i wonder which is worse? i was just pokin' fun anyway! the 5 boats i have right now are suckin' up all my money, and i want to build a good race boat this summer, plus upgrade my blizzard to brushless...but the paycheck says no more til the ones i have are all built/repaired.

[Hydro Junkie]

Calm down? What do you mean calm down? I AM CALM!!!!!IF I WASN'T CALM I'D.......I'D........Oh, never mind :D And yes, I know you were having fun, AT MY EXPENSE!!!!!!!!!! Now that I've got that out of my system, you should have heard the lecture I got this morning about spending almost $60.00 on West Systems Epoxy products. I brought it home and set it all on the kitchen table, in plain site and still in the bag. To make things even more interesting, it was set right next to one of the boats I'm building. I was accused of trying to hide it from her and keeping secrets from her :eek: Now Doc, aren't you glad you only have to worry about the size of your paycheck? ;)

[BoatDoc]

...and people ask why i've chosen to stay single! it's the hobbies, of course :D

[Hydro Junkie]

I think it's lack of onbase housing with TWO BEDROOMS, one for the boats and one for you and the BOSS :D You do have to look at what you're missing, though. Someone to launch your boat. Someone to wear a skimpy swimsuit while SHE launches you boat :) Someone to wear a skimpy swimsuit while helping to carry all the boats and gear to the water before SHE launches your boat :D Someone to wear a skimpy swimsuit while making a picnic lunch before helping to carry the boats and gear to the water before SHE launches your boat :D Someone to wear a skimpy swimsuit reminding you how much SHE HELPED YOU before telling you SHE EXPECTS A NIGHT OUT BEFORE HELPING YOU AGAIN :mad: Oh yeah, don't expect the skimpy swimsuit TILL SHE GETS WHATEVER IT IS SHE WANTS!!!!!

[FlyerCAN]

Do you have any pics of her wearing a skimpy swimsuit while SHE launches your boat? Just want to see the boat of course.. :D

[Hydro Junkie]

Unfortunately no. She nags at me for not having the boats finished, but she is scared of the thought of a spinning prop so close to her hands. Besides, unlike down in the south, it's too cold to get her into a swimsuit this early in the season. Anyway, I was just explaining to Boat Doc what he is missing down in the land of "Peaches". LOL

[BoatDoc]

GA may be the land of peaches, but here in this area...there are NO orchards :D what i'm missing is the great land of milwaukee!!!!...where the only thing that cuts into boat time is bar time!

[Hydro Junkie]

Sounds good to me, as long as BAR TIME IS AFTER BOAT TIME ;) I don't even want to think of someone driving a boat while intoxicated. Does anyone know if you can get busted for DUI while running an R/C :confused:

[BoatDoc]

what if there is a lake at the bar??? anyway, i'm still trying to figure out my power supply ordeal. i think i'll go with a 350w computer power supply. they have a good amp rating, and they're fan cooled. i just have to check the cash flow first.

[Hydro Junkie]

Better still, what if there's a lake IN the bar :D Getting back to the power supply, that's only 2.9 amps. Is that going to be enough power :confused: