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-   -   Pratt Hobbies Launch controller (http://www.oldrocketforum.com/showthread.php?t=10189)

bobdros 11-06-2011 06:51 AM

Pratt Hobbies Launch controller
 
I've always used the Estes launch controller. I could never be sure the batteries had enough juice to ignite the motor. I saw the Pratt Hobbies launch controller (Sirius Rocketry I think) and it was one of the best decisions I ever made! I use my lawn tractor battery and it's a guaranteed launch every time! I absolutely LOVE it!

If you've ever wondered about it, don't even think about it! Just do it!

blackshire 11-07-2011 11:46 PM

Quote:
Originally Posted by bobdros
I've always used the Estes launch controller. I could never be sure the batteries had enough juice to ignite the motor. I saw the Pratt Hobbies launch controller (Sirius Rocketry I think) and it was one of the best decisions I ever made! I use my lawn tractor battery and it's a guaranteed launch every time! I absolutely LOVE it!

If you've ever wondered about it, don't even think about it! Just do it!
That total lack of any perceptible delay (plus the confidence of being able to ignite clusters) is great! The old 12 volt Estes FS-5 Astron Launch Controller was that way, and I've been considering getting a Pratt Hobbies 12 volt system to regain those capabilities *without* the need for a car battery.

bernomatic 11-08-2011 05:19 PM

One of the few things I had from my younger years of launching was my Estes 12 volt launch system. I had bought a portable car battery booster which had 12 volt outlets on it. I rewired the clamps to a 12 volt plug and viola! Never had to worry about if I had the juice or not again (that is tuntil last year when I ran into some rough times trying to find work and... well anyway that's all behind me now :) ). The great thing was being able to recharge the booster by plugging it into the car, so if I ever needed a recharge...

Anyway, I'm still searching for an old launch set with the old launch system and hoping I find it when I have some money :D .

Doug Sams 11-08-2011 05:41 PM

Fs-5
 
Quote:
Originally Posted by blackshire
That total lack of any perceptible delay (plus the confidence of being able to ignite clusters) is great! The old 12 volt Estes FS-5 Astron Launch Controller was that way, and I've been considering getting a Pratt Hobbies 12 volt system to regain those capabilities *without* the need for a car battery.
That's the one I was using when I re-entered the hobby in late 1999. It had been in a box of child hood toys stashed in my attic. You can see mine in the pic below (2nd from left). Nearly 30 years of disuse had taken some toll - the key was missing and I had to replace the bulb, as I recall - but it managed to get my BAR birds successfully in the air. I later lengthened the leads (for E motor use) and swapped the battery clamps for banana plugs, but I still use it. To this day, I think it has a much better, more solid feel to it than the later models. Doug .



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Doug Sams 11-08-2011 05:50 PM

Quote:
Originally Posted by blackshire
...and I've been considering getting a Pratt Hobbies 12 volt system to regain those capabilities *without* the need for a car battery.
One thing to keep in mind, while 12V is definitely the starting point for a reliable launch controller, if you want truly high performance (for example, lighting clusters w/o benefit of low current ignitors) then build/buy/get a relayer. That way, the battery is close to the pad and you avoid the voltage/current robbing effects of long wires. Your handset can still be 50 feet or more from the pad, but the distance from the battery to the ignitor is only a few feet.

Doug

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luke strawwalker 11-08-2011 10:23 PM

5 Attachment(s)
I never had the "HD" 12 volt controller that Estes used to sell... I got a couple starter sets back in 86-87 when I was in rocketry before and have kept the controllers all this time. Even back in 88-89 I didn't like the standard "AA" battery power and reworked the controllers.

First, the dinky car speaker wire had to go. I replaced it with a couple rolls of 120 volt twin lead lamp cord I bought for a buck a roll at the dollar store. Second, I ditched the stupid "AA" batteries and wired it up with lamp cord and battery charger clips to run off the car/truck battery. Next, I hated the stupid flashlight bulbs-- sometimes I'd clean the clips two or three times just to find out the stupid bulb had 'jimmied' a bit in the socket and lost contact and was showing no continuity when there actually was. So, I gutted an old worn out VCR and grabbed all the LED's I could find in the thing, and some of the resistors, and soldered them together to make LED indicators and installed them in the launch controller. My favorite controller was actually the old "Pola-Pulse" flat battery controller that I got in a "Stealth" starter kit. I wired it first and replaced the bulb with twin LED's... one burning constantly any time it was hooked up to the car battery (indicating a good connection there) and the other one glowing with the ignitor hooked up with a good connection (continuity). I pretty much retired the old Solar controller since I didn't get around to putting LED's in it and the other one worked SO well.

When I became a BAR, I reworked the old Solar controller, this time with a pair of LED indicators from Radio Shack-- an amber one indicates battery power to the controller, the red one indicates continuity. I had leadouts to the clips and car battery, which I subsequently cut and added 120 volt male/female electrical plugs, to use a standard extension cord for ignition leads. The clips simply plug in the opposite end of the extension cord. This makes a VERY nice and easy to store controller. The large guage multistrand lamp cord and HD connections (120 volt connections) make excellent low-impedence high-current delivery possible even with a long extension cord. When my grandmother passed away, we found a car jumper battery pack in her closet someone gave her. I took it home, plugged it in, and it works like a champ! I use it for a VERY neat portable power supply for launching rockets, as well as boosting off tractors and trucks around the farm when the batteries are a bit low... handiest thing since sliced bread!

It's really not hard to do.
Later! OL JR :)

PS... I highly recommend that you ditch the steel safety keys... they tend to rust, they don't get good contact, and steel isn't anywhere near as good a conductor as copper. You can make your own safety keys for Estes controllers very easily from regular copper Romex 120 volt house wire. You can probably get some free scraps at your local lumberyard or big box store, or simply buy a foot of 14 guage Romex off the bulk spool. That'll be enough to make probably 5 keys! Romex is single-lead conductor, a little smaller than a pencil lead (depending on the guage). The bare ground wire is easiest to use, but sometimes it's undersize. If it is, skip it and use the black or white main conductor wires. Pull a piece out, cut it off about two inches long. Strip off all the insulation (wire stripper or carefully with a knife). Insert the bare conductor wire into the keyhole of the launch controller to ensure that it's going to fit and not be too tight or too loose. #14 SHOULD be a perfect fit (IIRC-- maybe it's #12). Anyway, form a loop in one end for the 'handle' of the key-- you can make is square by simply bending the wire with pliers like the Estes keys, or round by curling the wire around back on itself with pliers, and then bending the loop over a bit the other way to "center" the handle over the key 'shaft'. I used a soldering iron and bit of rosin core solder to solder the end of the loop back to the shaft of the key, just to ensure that the soft copper doesn't 'bend open' with use, and so it can be tied to a string or whatever if desired.

The new key will get contact MUCH easier and MUCH better than the old steel keys! You can see the copper keys in the controllers below!

bernomatic 11-09-2011 11:04 AM

Quote:
Originally Posted by luke strawwalker
When my grandmother passed away, we found a car jumper battery pack in her closet someone gave her. I took it home, plugged it in, and it works like a champ! I use it for a VERY neat portable power supply for launching rockets, as well as boosting off tractors and trucks around the farm when the batteries are a bit low... handiest thing since sliced bread!

It's really not hard to do.
Later! OL JR :)


If you look on the top panel of the portable power supply, I think I see a socket (covered) for a 12 volt plug. "Recycle" a plug from a old 12 volt gadget (or you can buy one at some auto stores),swap with the battery clips and now you have easier access to that 12 volt power by plugging into the portable power supplies' 12 v outlet. :cool:

Want even more versatility? Use RCA jacks on the end of the power supply lines and on the battery clamps and on the 12 v. plug, and now in mere seconds, you can switch to whatever power source you have.

BTW, If you don't have the 12 v. portable power supply (aka jumper battery, car booster battery...) still having the 12 v. plug makes it awful convenient to just plug into the car's cigarette lighter instead of opening the hood and messing around under there. I know my '95 lumina van even had an outlet in the back so when I opened the rear hatch to get to my supplies it was right there.

Doug Sams 11-09-2011 11:17 AM

Quote:
Originally Posted by bernomatic
If you look on the top panel of the portable power supply, I think I see a socket (covered) for a 12 volt plug. "Recycle" a plug from a old 12 volt gadget (or you can buy one at some auto stores),swap with the battery clips and now you have easier access to that 12 volt power by plugging into the portable power supplies' 12 v outlet. :cool:

Want even more versatility? Use RCA jacks on the end of the power supply lines and on the battery clamps and on the 12 v. plug, and now in mere seconds, you can switch to whatever power source you have.

BTW, If you don't have the 12 v. portable power supply (aka jumper battery, car booster battery...) still having the 12 v. plug makes it awful convenient to just plug into the car's cigarette lighter instead of opening the hood and messing around under there. I know my '95 lumina van even had an outlet in the back so when I opened the rear hatch to get to my supplies it was right there.
Hi, Bernard,

You need to keep in mind both these connector types have reliability issues. The cigarette lighter connectors are notorious for popping out at the wrong time. In this case, being halfway out is the really hazardous part since that's when there will still be some conductivity...perhaps just enough to get half your cluster lit :eek: Plus, if you're coming off the cigarette lighter socket, you stand to pop the fuse to it.

Similary, the RCA jacks get pretty loose after a while and can present similar current restrictions. And they're not all that high-current rated to start with. Our club model rails use these, and I frequently see where the center conductor has become quite loose and wobbly.

That's why I prefer banana plugs. They can handle lots of current, and they connect quite solidly, with nearly an inch of insertion length.

No doubt those other connectors have multiple advantages such as availability and ease of use, but I find them to be iffy if used for more than one motor at a time.

Doug

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luke strawwalker 11-09-2011 04:22 PM

Quote:
Originally Posted by bernomatic
If you look on the top panel of the portable power supply, I think I see a socket (covered) for a 12 volt plug. "Recycle" a plug from a old 12 volt gadget (or you can buy one at some auto stores),swap with the battery clips and now you have easier access to that 12 volt power by plugging into the portable power supplies' 12 v outlet. :cool:

Want even more versatility? Use RCA jacks on the end of the power supply lines and on the battery clamps and on the 12 v. plug, and now in mere seconds, you can switch to whatever power source you have.

BTW, If you don't have the 12 v. portable power supply (aka jumper battery, car booster battery...) still having the 12 v. plug makes it awful convenient to just plug into the car's cigarette lighter instead of opening the hood and messing around under there. I know my '95 lumina van even had an outlet in the back so when I opened the rear hatch to get to my supplies it was right there.


You are correct sir... it does have a cig lighter plug. I have the parts to do it but I haven't gotten around to it yet. The "clip the clamps on the clips" thing actually works very well and still allows me to use a regular car battery if need be.

The thing actually charges through the cig plug. Has a double-ended cig plug connected with speaker wire, that can jumper from the truck cig lighter to the jumper pack receptacle to charge on the drive out, or a wall-wart with a cig plug on the end that plugs into the battery jumper box to charge it in the house.

Later! OL JR :)

John Brohm 11-09-2011 07:10 PM

1 Attachment(s)
Quote:
Originally Posted by Doug Sams
One thing to keep in mind, while 12V is definitely the starting point for a reliable launch controller, if you want truly high performance (for example, lighting clusters w/o benefit of low current ignitors) then build/buy/get a relayer. That way, the battery is close to the pad and you avoid the voltage/current robbing effects of long wires. Your handset can still be 50 feet or more from the pad, but the distance from the battery to the ignitor is only a few feet.

Doug

.


Couldn't agree more. It's all about maximum amp delivery to the igniter. The photo below shows the guts of an away pad controller I built to interface with our already existing Competition Launch System. The Away Pad Controller is intended to be used for our higher power launch pad, which we can place as much as 100 feet away from the LCO (the distance is only limited by the present length of the control cable from the LCO desk). In the photo you'll see a pair of heavy #10 wires coming in from the local battery connector, which then get routed via the pair of relays to the igniter lead sockets. It's a very short current path, and the system dumps exceptional levels of current to an igniter and/or a cluster of igniters when the resistance path (to your point) is so short. We've not had a failed ignition event.


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