# Simple, safe 12v controller!! With pics, wiring diagram, and part numbers =)

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#### grimlock3000

##### Well-Known Member
All of the information in this thread came right from this forum, it was just spread out over a bunch of threads. I have gone through a couple previous failed efforts at building my own 12v launch controller. This thread is about what I ended up with. The controller that can handle clusters, is perfectly NAR compliant to the best of my knowledge, and easy to build with Radio Shack parts and really basic soldering skills. I am going to post everything up here and hopefully it will help someone else so they do not have to go through all the rewiring and frequent trips to Radio Shack like I did. This controller should cost about $25 but it can be cheaper if you already have some of the stuff. After buying the wrong parts and messing up a few things along with wasted gas, my total money spent is around$55

First up, the list of parts and prices...

*Project box* $3.69: https://www.radioshack.com/product....1_002_012_000&product_id=270-1803&site=search *Interlock key* I have the contacts soldered together inside the top to complete the circuit when the key is inserted$2.99:

*Interlock holder* The online pic is wrong for this, the real thing has only two contacts for a mono plug. Make sure you wire the bottom plug to the firing switch when you use this $2.99: https://www.radioshack.com/product....11_003_001_009&product_id=274-252&site=search *Continuity check LED with built in resistor*$1.99:

*Continuity check Piezo buzzer* $4.29: https://www.radioshack.com/product.asp?catalog_name=CTLG&product_id=273-060 *Momentary launch button* 12V DC @20A, or @40A if wired in parallel. You can also wire this to fire when pressed up, down, or either$4.49:

That comes out to $20.44 before tax. Since the continuity checks are redundant, you can choose to use the LED OR Piezo buzzer if you want so the price can be even lower. Not listed is the 16g speaker wire I used ($5), a few washers (25 cents each), the alligator clips ($2), and 12v plug ends ($2). You can use whatever fits you application for alligator clips and 12v ends, just make sure it can handle the current of launching a rocket. For wire, use 18g or thicker. I went with 16g to be on the safe side.

Here is the wiring diagram of the final design. Red is positive, black is negative, and green is conditional (not connected unless the key is inserted or switch if pushed):

The LED and Piezo combined only draw an average of 17mA which is OK for the continuity check. I tested the controller a bunch and did not find the Piezo very loud at all. It is very easy to put the buzzer on a switch if you want to be able to turn it off.

And finally, here are the pics of the real thing...

*Internal wiring* I used electrical solder for everything instead of push on connectors. I also used epoxy to secure some wiring and the buzzer so nothing shakes around inside the controller. I connected the leads of the momentary switch so it works if you push it up or down:

*Outside shot and interlock* I used large washers to keep everything secure on the lid of the project box. Using a mono plug for the interlock key works really well too, it is a very solid connection:

*12v power source* This is the starter box for my RC nitro truck. Inside the starter box is a 12v sealed lead acid battery. This could just as easily be a car battery if you wanted:

*Mess* You can see the controller panel from my first failed controller in this shot:

Thanks to everyone who helped me out with this, now I hope I can help out some other people

//Update//

*Clip whip* I put this together with two butt connectors, some heat shrink tubing, colored zip ties, and mini alligator clips:

#### Silverleaf

##### Well-Known Member
Though I know nothing about electronics - and even less about schematics, that looks really nice. I like the look of the finished controller, and you've certainly made this easy for anyone whom wishes to build their own.

Well done !

8)

#### grimlock3000

##### Well-Known Member
People have asked a few questions about similar designs lately, so I am bringing this post back from the dead

I have used this controller a few times and never had an issue. It lights off three Estes igniters without hesitation. Having the dual continuity check (LED + buzzer) has proven to be extremely useful, particularly when new rocketeers are launching.

#### Mike

##### Well-Known Member
Grimlock, thanks for this but it looks like the picture links have changed since you first posted it.

#### powderburner

##### Well-Known Member
Does grimlock get the community service award for this month?

Nice job, grimlock, and thanks for sharing all this work

##### Well-Known Member
Nice job. I'll be building something similar soon. I can't see your picture(s) or diagram(s) from here, so I'll have to check those later.

A few suggestions for minor improvements.
1.) Use a bright clear LED. I've heard some say that LEDs in colors are harder to see in some lighting conditions.
2.) Look for a switch or button that doesn't stick out past its mounting. That way, if the controller is dropped to the ground with the key still in it (as the kids at our launches almost invariably do) there's less chance of the switch being activated again as the controller handset lands and perhaps lies on its face.
3.) Add a fuse or circuit breaker.

##### Well-Known Member
Still can't see the pictures. Can you replace them? I'd really like to see what you did with this system.

#### grimlock3000

##### Well-Known Member
I moved this weekend, my pics died with my internet service I will try to get these up soon on another server.

##### Well-Known Member
GOOD. You chose to use a removable interlock in the form of a Phone Plug for the safety key! many people make a mistake when they buy from Radio Shack and go for the key switch that is on the store shelves.

BEWARE: The radio shack stores do not carry N.F.P.A. 1122 or NAR compliant safety switches BECAUSE the keys can be removed with the switches ON. The only safe/legal key switch is one where you CANNOT remove the key when it is on. In other words, whenever the key is out, it is safe/off. Good electronics suppliers do indeed carry the good switches.

#### grimlock3000

##### Well-Known Member
BEWARE: The radio shack stores do not carry N.F.P.A. 1122 or NAR compliant safety switches BECAUSE the keys can be removed with the switches ON.
I can pull the key out of my Estes launcher too, does that mean it is not NAR compliant? I had a few threads earlier this year about the safety of the controller. I actually redesigned it twice before arriving at this, surprised this did not come up sooner.

#### powderburner

##### Well-Known Member
Can you guys edit your posts and attach the pix as .jpg files or something? Your attached photos are opening very very slowly (or not at all)
I would sure appreciate being able to see your work

#### grimlock3000

##### Well-Known Member
I messed up and forgot to transfer my pics to a new server when I moved last week. The pics are gone, but I have everything backed up on my PC at my house. If I get around to hooking up my PC tonight, I will burn the pics to a CD and upload them to a new server.

##### Well-Known Member
Safe = Key in/armed. Key out/dead.

If you can pull the key out and it is still able to fire when you push the button, then it is unsafe.

Estes = safe.

Design featured with removable phone plug = safe.

Key switch where the key can be removed in either the on or off position = unsafe.

This is what I said the first time. I'm saying it again with extreme clarity since it appears there was a reading comprehension problem.

Originally posted by grimlock3000
I can pull the key out of my Estes launcher too, does that mean it is not NAR compliant? I had a few threads earlier this year about the safety of the controller. I actually redesigned it twice before arriving at this, surprised this did not come up sooner.

#### grimlock3000

##### Well-Known Member
Key switch where the key can be removed in either the on or off position = unsafe.

This is what I said the first time. I'm saying it again with extreme clarity since it appears there was a reading comprehension problem.
Sorry, I did not understand the entire purpose of the BEWARE section unless it pertained to something I did. In particular...

BEWARE: The radio shack stores do not carry N.F.P.A. 1122 or NAR compliant safety switches
Maybe if you said, "This setup is safe and NAR compliant. Anyone else viewing this, please note that some of the items Radio Shack sells are not safe"

I designed the thing, and I was confused after reading the beware section. I thought you were saying, "Nice try, but you still screwed up..."

#### rkt2k1

##### Well-Known Member
Fred,

Ease up dude! Remember this isn't RMR. It was just a request for clarification by a fellow rocketeer on the information you posted.

##### Well-Known Member
Exactl'y where was I not "easy".

PLEASE read my first message from beginning to end. It was not very long and it began with the word "GOOD".

My second post simply stated the facts again in a crystal clear manner. What should I have done? Not restated the facts clearly?

I thought I did a GREAT job of communicating and explaining. If I get insulted because people read too fast to understand what they are reading or if they skip words while they are reading and therefore are unable to understand what I wrote, then my only obligation is to try to restate the facts again in an attempt to help them read and understand.

Notice that the first time I posted it was in paragraph form. Perhaps that was too complex. The second time I broke it into small equation-like lines to make it easier to get through each point before losing the reader.

It worked.

Nothing to "ease up" on either time (or even this time). I think the readers should "ease up". I've seen this before on other forums and newsgroups. Once in a while a reader who is having a bad day, will read something and infer or read into it some emotion that is not there. the safest way to read messaged that are typed into the web or Usenet is to assume there is NO emotion unless they add emoticons or other clear indications.

OK?

Originally posted by rkt2k1
Fred,

Ease up dude! Remember this isn't RMR. It was just a request for clarification by a fellow rocketeer on the information you posted.

#### Micromeister

##### Micro Craftman/ClusterNut
TRF Supporter
GOOD. You chose to use a removable interlock in the form of a Phone Plug for the safety key! many people make a mistake when they buy from Radio Shack and go for the key switch that is on the store shelves.

BEWARE: The radio shack stores do not carry N.F.P.A. 1122 or NAR compliant safety switches BECAUSE the keys can be removed with the switches ON. The only safe/legal key switch is one where you CANNOT remove the key when it is on. In other words, whenever the key is out, it is safe/off. Good electronics suppliers do indeed carry the good switches.
Fred:
This is another case where you Sould have stopped at the first paragraph. Your second paragraph is unnecessary and confusing to folks especially the younger ones reading about a very nicely designed and constructed controller. Come on man lighten up, I'm inclined to think ya really should build more and talk less

Excellant job Grimlock! keep up the good work. sure wish I could have seen the completed controller photos.

##### Well-Known Member
I safety check several thousand models every year and all of the launch systems and pads brought to our NAR section's launches.

90% of the home-made launch controllers that use a key-switch use the wrong kind. The builders are told what's wrong and handed a card for an electronics store that sells the correct switches and they *all* say "I wish someone had told me about that earlier since it slipped right by me". 10% with a key switch use the good kind, and just like I said in my original message, I say "GOOD" and tell them why it was a good choice for a switch. The usual response to that is "Thanks" or "Thanks, I had no idea I just lucked out" or "Thanks, I knew about that and chose the switch intentionally".

If I can provide correct information that is explained clearly and that will save people time and effort (i.e. prevent them from making mistakes), then what exactly needs to be "lightened up"?

Should I lighten up on the NAR Model Rocket Safety Code?

Of course, if I provided incorrect advice or suggested doing something dnagerous or illegal, then go right ahead and jump all over me.

Originally posted by Micromeister
Fred:
This is another case where you Sould have stopped at the first paragraph. Your second paragraph is unnecessary and confusing to folks especially the younger ones reading about a very nicely designed and constructed controller. Come on man lighten up, I'm inclined to think ya really should build more and talk less

Excellant job Grimlock! keep up the good work. sure wish I could have seen the completed controller photos.

#### Micromeister

##### Micro Craftman/ClusterNut
TRF Supporter
I safety check several thousand models every year and all of the launch systems and pads brought to our NAR section's launches.

>>>> Ditto, I do also... however I see less then 5% of these new controllers that use only the "wrong kind" of interlock switch, Further of those, it's a VERY easy fix to add a pull-out plug of several types to bring the unit into compliance, leaving the existing keyed switch as a power-on redundant switch. I use that very set up set-up myself on some systems.
The reason your being "jumped on" here is: NO Such device was used or mentioned by the author of this thread. He did a wonderful job of working to the rule.

90% of the home-made launch controllers that use a key-switch use the wrong kind. The builders are told what's wrong and handed a card for an electronics store that sells the correct switches and they *all* say "I wish someone had told me about that earlier since it slipped right by me". 10% with a key switch use the good kind, and just like I said in my original message, I say "GOOD" and tell them why it was a good choice for a switch. The usual response to that is "Thanks" or "Thanks, I had no idea I just lucked out" or "Thanks, I knew about that and chose the switch intentionally".

If I can provide correct information that is explained clearly and that will save people time and effort (i.e. prevent them from making mistakes), then what exactly needs to be "lightened up"?

>>>>>As with many who think we are explaining something "clearly" it's sometimes as clear as MUD to those reading a misplaced unnecessary comment, as is the case here. that's what I ment by I think you should build more and talk less. Or maybe comment on things when ASK. Lets try to keep our comments as positive and reinforcing as possible without all the editorial commentary.

Should I lighten up on the NAR Model Rocket Safety Code?

>>>> of coase NOT, we don't lighten up on the Safety Code...but we don't need to shout fire in the threater either, which makes people nervous. If we wish to make a point or sight something specific in the design at hand that needs attention fine...NONE was needed it this thread. That's were you need to Lighten up.

Sort of like "NO one" in this country will accept a Silver or Gold (Coin) Dollar smaller than 38.1 mm., I just don't know what the US Mint it thinking A true statement (opinion) but totally off the mark. Well maybe further than going off about Keyed switches but you get my drift.

##### Well-Known Member
In the hope that a third (fourth?) party's perspective may prove helpful, here goes.

I understood shreadvector's post complimenting the design and moving on to a general warning for the general case. I thought both parts were helpful. A transitional sentence like "Your design looks good, however it should be noted that . . ." might have helped here.

When grimlock3000 misunderstood, shredvector's next post was OK up to the line "This is what I said the first time. I'm saying it again with extreme clarity since it appears there was a reading comprehension problem.", which might have been better worded as "Just a clarification. Your design looks good." or something similar.

Like rkt2k1 and Micromeister, that line in its original form struck me as heated and a bit over-reacted, though when I re-read it, I can see how it might well not have been meant that way.

rkt2k1's "Ease up dude!" seemed about right in response, in order to alert shredvector to the way the tone 'sounded'.

The rest of the thread seems a bit defensive on all sides and like getting wrapped around the axle. I recognize the pit because I've fallen into it myself plenty of times, though never here and not recently. It seems clear to me that no harm was intended here on anyone's part.

All agree that safety is paramount, that getting safety info out prior to people building systems is a good thing, and that the design in question looked nice.

We've got a great hobby here, and the camaraderie is one of the finest aspects of that.

grimlock3000: shredvector's a good guy, who wanted to share useful information with you (and with other readers of the forum) along with a compliment. rkt2k1 and Micromeister are good folks too, who are looking out for you and want to see you succeed. This is the best place on the net to share ideas and get good constructive advice.

MR -- The Peacemaker

#### grimlock3000

##### Well-Known Member
Glad to see this is all getting worked out I am getting DSL tomorrow at my new house, then I can upload the pics if everything goes well with that. One of the pics is a wiring schematic as well, it is very easy to follow and see what I did.

##### Well-Known Member
I'm looking forward to seeing your re-posted pictures. How about posting pics of the new house too?

On a different topic, I'm a computer engineer by trade, so I hope you've heard that you NEED a firewall if you're using DSL. I like ZoneAlarm from Zone Labs, but there are plenty of good ones out there. You'll need good virus program too, for which I recommend Norton. I use PestPatrol and AdSubtract too. Forgive me; I'm probably preaching to the choir here and telling you stuff you know, but too many folks out there are getting bitten on this one.

#### grimlock3000

##### Well-Known Member
I got my DSL modem last night, my service gets turned on today I do not have my computer desk in place yet, so I am going to setup my PC right in the kitchen.

I got everything safe and secure in the PC. I use Computer Associate's antivirus software and a firewall.

PICS FIXED

#### Rocketman35

##### Well-Known Member
Thanks grimlock3000
I'll be building this controller very soon.
Thanks again for your hard work!

Chuck

#### powderburner

##### Well-Known Member
Originally posted by grimlock3000
*Mess* You can see the controller panel from my first failed controller in this shot
Everything in that picture looks pretty normal to me