News:



  • March 29, 2024, 01:41:13 AM

Login with username, password and session length

Author Topic: Want to drop 2 vdc. to 1.5 vdc. How?  (Read 1635 times)

Offline frank mccune

  • AMA Member
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1621
Want to drop 2 vdc. to 1.5 vdc. How?
« on: September 26, 2018, 09:39:33 AM »
     Hi All:

     I want top drop a 2 vdc source to 1.5 vdc for glow plug use.  I have had many suggestions that were strange and not desireable.

     One suggested an  .016 ohm resistor,  One suggested a .5 ohm resistor, a length of lamp cord etc I think the resistor would have to be  about a 5 amp capicity ?

     I am looking for a small device that may carried in hand or pocket.  Perhaps I should just purchase one of those recharable head lock type of batteries or purchase Fireball Plugs that take up to 3 vdc. Wdhere does on purchase on of the rechageable head lock type of starting batteries?

     Will a 2vdc bttery damage plugs like K&B, O,S etc.?

      Suggesatione/comments??

                                                                                                                                          Tia,

                                                                                                                                          Frank McCune

                                                                                                                                           Frank McCune

Online Brett Buck

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 13717
Re: Want to drop 2 vdc. to 1.5 vdc. How?
« Reply #1 on: September 26, 2018, 09:54:29 AM »
     Hi All:

     I want top drop a 2 vdc source to 1.5 vdc for glow plug use.  I have had many suggestions that were strange and not desireable.

     One suggested an  .016 ohm resistor,  One suggested a .5 ohm resistor, a length of lamp cord etc I think the resistor would have to be  about a 5 amp capicity ?

     I am looking for a small device that may carried in hand or pocket.  Perhaps I should just purchase one of those recharable head lock type of batteries or purchase Fireball Plugs that take up to 3 vdc. Wdhere does on purchase on of the rechageable head lock type of starting batteries?

   A substantial silicon diode will drop about .6 volts, something like a 10A05, should be about a nickel at the electronics supply house. A resistor will work, you need about about .1 ohm, but long zip cord leads will get you about right. I don't like that solution because the voltage changes with current and it gets moderately hot.

   But, if you aren't stuck with 2v lead-acid cells, I have used the McDaniel Ni-Starters for years, and the new Li-Ion versions are quite excellent, long-lasting (if you don't overcharge them repeatedly) and reasonably cheap.

      Brett

p.s. resistors aren't rated in amps, they are rated in watts. In this case, if you are drawing 4 amps (about what you get on a moderate rich setting)  you will be dissipating about 1.6 watts which will get pretty hot pretty quick. A 5 watt resistor would do the job, but you would not want to touch it after about a minute. The long zip cord will dissipate the same power, but over 2-3 feet of wire, so the temperature would not be too high.


They used to make radios that way, the cord had a logn resistor element in it, along with the regular power, and they dropped maybe 30 watts. When it worked, and the cord was not all coiled up, it was *accceptable*.   But they were called "curtain burner" radios for a very good reason.
« Last Edit: September 26, 2018, 10:32:15 AM by Brett Buck »

Offline john e. holliday

  • 24 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 22752
Re: Want to drop 2 vdc. to 1.5 vdc. How?
« Reply #2 on: September 26, 2018, 10:17:29 AM »
I vaguely remember the 2 volt wet cells that Charley's Hobby Shop carried.   We just used a long electrical cord, About 4 foot in length. D>K   
John E. "DOC" Holliday
10421 West 56th Terrace
Shawnee, KANSAS  66203
AMA 23530  Have fun as I have and I am still breaking a record.

Offline frank mccune

  • AMA Member
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1621
Re: Want to drop 2 vdc. to 1.5 vdc. How?
« Reply #3 on: September 26, 2018, 12:53:29 PM »
      Hi Brett and John:

      Thanks for the prompt replies!

      I forgot that resistors are indeed rated in watts.  I found a new resistor lying on my work bench that is marked .1 ohm 10% 5 watts.  Was that a form of "Devine Intervention?" This gives me something to play with this Winter.

      I sometimes use a small rechargeable round lead acid battery that is rated at 2vdc and 5 amps.  I thought that it would be a good idea to carry it in a front pocket in my pants.  Wrong!!! Somehow the battery and the keys in the pocket made contact and the heat was perhaps, astounding!!!!! I could not have babies for years after that experience!!! Lol

      I do have a couple of the rechareable glow plug igniters that were feature in an article above re,changing batteries in them.  I also have two chargers for these things.  More Winter projects!

     Back in the Day, I was introduced to the latest in the field of speed control for small tools.  It was called a Zenner Diode.  It was supposed to limit voltage without any additional loss due to heat etc.  Have any of you used a Zenner Diode in a glow driver.  They were adjustable to suit your requirements.

                                                                                                                                   Be well,

                                                                                                                                   Frank McCune


                                                                                                                             

Online Howard Rush

  • 22 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 7805
Re: Want to drop 2 vdc. to 1.5 vdc. How?
« Reply #4 on: September 26, 2018, 02:36:41 PM »
I want top drop a 2 vdc source to 1.5 vdc for glow plug use. 

I don't think that's what you want.  Here is my opinion on the requirements for combat:

1. Regulated 1.0 volt at the plug.  This works for most all plugs except Fox Racing and Cox.  Resistance between the voltage source and plug is bad: it causes the plug to cool when the engine is flooded.  Constant-plug-resistance schemes burn out plugs.
2. Long cable.  This lets you stand up while starting and minimizes bother.
3. Light cable.  This prevents the weight of the cable from pulling off the clip.
4. Ammeter.  This tells you if the engine is flooded or if the plug is tango uniform.
5. Analog system, rather than pulse width modulation.  Higher voltage pulses make sparks, which cause fires.
6. Foldover short-circuit protection.

For stunt, the twist-on orange-blob NiCad starter is perfect.  You don't need an ammeter because plugs last a long time and you get to determine when to start the engine, so you can feel for a bump when you turn the prop and decide if you're ready.  You don't need a quick-release clip: there is plenty of time to twist off the starter after the engine starts.  You don't need the short-circuit protection because there is no opportunity for a short until you put the starter in your pocket.
The Jive Combat Team
Making combat and stunt great again

Online Brett Buck

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 13717
Re: Want to drop 2 vdc. to 1.5 vdc. How?
« Reply #5 on: September 26, 2018, 02:55:14 PM »
      Hi Brett and John:

      Thanks for the prompt replies!

      I forgot that resistors are indeed rated in watts.  I found a new resistor lying on my work bench that is marked .1 ohm 10% 5 watts.  Was that a form of "Devine Intervention?" This gives me something to play with this Winter.

 

   Or mock it up this afternoon just to see how it works and how hot it gets.

 

 
Quote
    I sometimes use a small rechargeable round lead acid battery that is rated at 2vdc and 5 amps.  I thought that it would be a good idea to carry it in a front pocket in my pants.  Wrong!!! Somehow the battery and the keys in the pocket made contact and the heat was perhaps, astounding!!!!! I could not have babies for years after that experience!!! Lol

     That's 5 amps, safely, for a reasonable amount of time. That doesn't mean it will give just 5 amps into a dead short - a Ni-Cad would probably give you a good 15-20 amps or more, until it burned something up.

    Brett

Online Steve Thompson

  • 24 supporter
  • Trade Count: (0)
  • Commander
  • *
  • Posts: 163
Re: Want to drop 2 vdc. to 1.5 vdc. How?
« Reply #6 on: September 26, 2018, 04:07:36 PM »
The no-longer-made GloBee Fire Plug Covered much of this.  2 volt lead acid battery, rheostat to set current, ammeter to watch, fuse in case of shorts.  It is quite a bit larger/heavier than a clip on NiCad but the charge lasts a long time.  I found a source for a replacement battery (Cyclon) and got mine back in service. 

Online Howard Rush

  • 22 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 7805
Re: Want to drop 2 vdc. to 1.5 vdc. How?
« Reply #7 on: September 26, 2018, 05:54:43 PM »
The no-longer-made GloBee Fire Plug Covered much of this.  2 volt lead acid battery, rheostat to set current, ammeter to watch, fuse in case of shorts.  It is quite a bit larger/heavier than a clip on NiCad but the charge lasts a long time.  I found a source for a replacement battery (Cyclon) and got mine back in service. 

People who use these often use 10-gauge speaker wire with them, which I guess is what you’d expect.
The Jive Combat Team
Making combat and stunt great again

Offline dave siegler

  • 2016 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1128
  • sport flier
    • Circlemasters Flying club
Re: Want to drop 2 vdc. to 1.5 vdc. How?
« Reply #8 on: September 27, 2018, 12:10:43 PM »
So a plug will pull several amps. 

The common setup was 2 .22ohm resistors.  set them up in series with a bypass switch to one if the plug floods out.   Radio shack used to have them.

the resistors need to be big, like 5 Watts or better.  10 to 20 Watts preferred.     

A glowbee used a 20watt 5 ohm rheostat, not so common now a days.   

Active regulators are better now.  there are several, and they are a lot better for battery life.   
« Last Edit: September 27, 2018, 12:39:20 PM by dave siegler »
Dave Siegler
NE9N extra class
AMA 720731
EAA 1231299 UAS Certificate Number FA39HY9ML7  Member of the Milwaukee Circlemasters. A Gold Leader Club for over 25 years!  http://www.circlemasters.com/

Offline Garf

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1817
    • Hangar Flying
Re: Want to drop 2 vdc. to 1.5 vdc. How?
« Reply #9 on: September 28, 2018, 09:55:38 AM »
Try This:

Offline Tim Wescott

  • 2016 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 12804
Re: Want to drop 2 vdc. to 1.5 vdc. How?
« Reply #10 on: September 28, 2018, 11:23:21 AM »
Try This:

Figure 5, page 6, here.  That part has a drop out voltage* of 1.7V or so at 1A out, more like 3V at 5A.  It would never manage to power a glow plug from 2V.  There are adjustable linear regulators out there that'll perform much better.  I'd say it was overkill, but I have visions of switching regulators dancing in my head, so I guess I'm not one to talk.

* In a 3-terminal linear regulator, the drop out voltage is the amount of voltage that the part has to drop from input to output in order to regulate.  To get your desired output voltage, the input voltage must be output voltage + dropout voltage.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline John Craig

  • 2017
  • Trade Count: (0)
  • Commander
  • *
  • Posts: 196
Re: Want to drop 2 vdc. to 1.5 vdc. How?
« Reply #11 on: September 29, 2018, 05:28:28 AM »
  "A substantial silicon diode will drop about .6 volts, something like a 10A05, should be about a nickel at the electronics supply house. "

I found an article about 25 years ago in an R/C magazine (R/C Sportsman?) that suggested this type of a system.  I built mine with Radio Shack black box, amp meter off an old Kraft unit for the large dry cells, 2 D cell nicads in series, a big diode, 2 pole trailer hitch connector from an auto parts store; allowing me to change glow plug clips, & an Ace HD charger. I've used it for 25 years.  The batteries no longer hold a charge as they once did. Never blew a plug from the higher than 1 1/2 volts recommended for most plugs. The voltage was in the 1.7- 1.9 range.  I have finally moved on to a Radio South orange box that I found on da Bay.  It needed new batteries & a charger.  It has all the bells & whistles in a small box; with 4 2200 ma C cells I will need to charge it about once every 3 months.


Advertise Here
Tags:
 


Advertise Here