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LS-8 and hairdriers

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#1 zyzyz

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Posted 29 September 2013 - 07:37 PM


I bought a used ls-8 thru craigslist and I would like to know how sensitive the electronics are to rf spikes on the power line. I have the Meade 115V power supply and would like to know if it's safe to use it on the same extension cord as a hairdrier?

The first night out it got so wet that I was going to use a hairdrier to clear off the dew but became concerned about the spikes the drier produces. Is it safe on the same line or would it be best to unplug the ac and use battery power while drying? I've found that some electronics are more robust than others. How tough is it?

Thanks in advance

Larry

#2 nitegeezer

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Posted 29 September 2013 - 08:51 PM

Many users users have a battery pack for powering the scope electronics for the very concern you mention. I would not expect a hairdryer to produce any power spikes that the Meade power supply would not reject. Hairdryers are primarily a resistor that gets hot with a small fan to provide air flow. It does not produce the large current spikes that a large inductive motor would generate. I would not be concerned about the hairdryer, but I always use a battery pack as I find it more convienent

#3 zyzyz

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Posted 29 September 2013 - 10:16 PM

Thanks for the info. I've worked with some cmos electronics and they can be very unforgiving to spikes. Good to know the ls series is tough enough to take a 'little' abuse.

#4 nitegeezer

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Posted 30 September 2013 - 12:43 AM

I am not sure how tough the ls series is, my point was that a hairdryer does not generate serious spikes. Now if you were to connect a fan blade to an electric drill, the brush contacts generate sparks which can make large spikes and then I would be concerned.

I just noticed you are new to CN, welcome aboard.

#5 Cliff Hipsher

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Posted 30 September 2013 - 08:58 AM

I am not sure how tough the ls series is, my point was that a hairdryer does not generate serious spikes. Now if you were to connect a fan blade to an electric drill, the brush contacts generate sparks which can make large spikes and then I would be concerned.


You might want to break out Electronics 101 and read it.

Hair driers have switches. Switches make arcs. Arcs generate broad spectrum Radio Frequency. Ever hear of a guy named Marconi?

Regardless how how well the output filter is, NO power supply can shield a load from external RFI.

A dew heater is a much better solution. You can learn how to build a controller here: Dew Controller

#6 zyzyz

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Posted 30 September 2013 - 10:35 AM

Thanks for the welcome. After months looking through the classifieds and salivating, I was finally able to obtain my 'dream' scope and all the questions that come with it. With the help of this board, I'm sure I can get all the info and tips I need to get me up and searching for my faint fuzzies. I've only used 'toy' scopes in the 60 - 70 mm range before and this 200 mm is a whole new species to me.

I would never use a large motor on the same circuit. I was more concerned about the small motor in the drier producing rf on the line. Didn't really consider the spikes on the power switch. I've worked on some programmable controllers that were very sensitive to line irregularities. If you were to use a drill on the same circuit you ran a real risk of corrupting the stored program on the controller. I don't want to be in the dark with a crashed telescope. One dummy in the dark is enough!

I'll use both of your advices. I plan on using a battery tank for scope power and the 115V line to run a dew heater. I'll look into the link for building one. Thank you for your input.

Larry

#7 astrogeoguy

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Posted 30 September 2013 - 09:08 PM

Get/make yourself a dewshield. My LS8 has one made from clipped together black craft foam. Cheap, light, and very effective without a dew heater.

Chris

#8 Cliff Hipsher

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Posted 01 October 2013 - 06:43 AM

You're welcome.

FWIW, I just ordered this., and I'm off to Wally World for a marine battery. I did some experimentation this past weekend, and I discovered my DIY heater control will also run my DSI Pro TEC cooler and fan. I know my Harbor Freight jump battery will run the mount all night, so all I need to do now is see how long my laptop will run on battery....

#9 zyzyz

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Posted 03 October 2013 - 11:58 AM

The circuit breaker is pretty high on that unit. 15 amps. You got a Clark 24 incher on gem mount? Just got back from a road trip to Az where we went to Kitt Peak and Lowell Observatory. You feel very tiny and awed when viewing those instruments. Didn't know if my wife was gonna survive the trips up and down the mountain road. Over 6000 feet in elevation in 11 miles of curves and switchbacks. Very exciting ear and eye popping drive.

I've got a tractor sales and repair shop just down the road from me where I can pick up a lawn tractor battery. Was gonna cobble together a wooden box with two or three 12v cig lighter receptacles and maybe a small red light to keep folks from bumping into things when they stop by to see what I'm looking at.

#10 cavefrog

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Posted 03 October 2013 - 11:40 PM

Tractor batteries, I would suppose, are a lot like car batteries. just more CCA. and meant to be kept at full charge all the time. drain them down past 50% very often and you will kill it fairly quickly. Marine batteries are meant for running trolling motors (slow drain) for extended periods of time. I will last a lot longer.

Theo

#11 zyzyz

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Posted 04 October 2013 - 03:27 AM

@asrtogeoguy
Good idea but, ... The ls series has only a small lip at the end of the ota and there's a plastic cover that runs down the side of the tube that prevents using a traditional method of mounting one. Trying to develop an idea to use a 'bra' to hold it on. Gotta make sure it doesn't 'jiggle' when attached.

@Cliff
Have you considered an inverter to power your laptop? The site inverters.com has some 400 - 750 W units for 40 - 70 bucks. Should keep your laptop alive for awhile after it's battery gets low.

@cavefrog
Didn't know that marine batteries would be a better choice over a car or tractor battery. If I can find a local dealer with a good price, I may have to rethink the project. The tractor dealer is less than 1/2 mile down the road so it's pretty handy. Any idea how much longer the life might be considering both batteries have the same amp/hrs? Will they be about the same size and weight? Thanks for the tip.

Larry

#12 astrogeoguy

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Posted 07 October 2013 - 09:52 PM

Mine goes right over the thick bracket. Jiggle will not affect any views.

#13 zyzyz

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Posted 08 October 2013 - 12:12 PM

I want to make an extension of the tube held in place with cloth straps. I've got a NIB glass solar filter that I want to use. I don't see any way to mount it without creating a 3-4 in lip extending beyond the ota. I was going to use it to hold the dew shield in place also. Still brainstorming that idea.

I'll pick up some foam and try it without a bracket first.






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