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TelRad Improvements

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#1 GetSomeSleep

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Posted 26 June 2013 - 08:43 PM

I was at a star party this Spring and I was using my TelRad for the first time in a while. The TelRad is an iconic piece of amateur astronomy equipment. I've owned many and had the one I was using for over 15 years. However, I was wondering if anyone had thought of possible mods to the TelRad. I had some ideas.

First, the zinc plated screws on my TelRad were showing signs of rust. I replaced them with stainless steel 4-40 hardware. Next, the tiny plastic knobs have always annoyed me because they are difficult to get a grip on, especially when wearing gloves. A set of stainless steel Bob's Knobs fixed that. I did see something on the Web about a guy putting plastic tire stem caps over the adjustment screws to improve the grip. I briefly thought about the skull tire stem caps, and how they would look on a TelRad - cool, but probably not practical. Finally, I made my own LED flasher from a PIC 12F625 microcontroller. Yes, I know you can buy LED flashers already, but the microcontroller can give you lots of different selectable patterns, including pulse width modulation that brightens and dims a flashing pattern automatically. Plus, the microcontroller has an automatic shutdown after a set time. Wouldn't it be great if your TelRad turned itself off if you forgot to, or the on/off knob got bumped? Mine does and it cost me less than $20 in parts.

The purpose of this post was to ask people for a new take or incremental improvements on an old war horse, the TelRad. What about a different colored bullseye, like green? What about a built-in dew heater? How about dimming the LED with a pulse width modulator instead of a variable resistor so that the LED dims smoothly when you turn the "volume" control, instead of blast on and hard off? I've seen the TelRad extenders - what a great idea to save wear and tear on your back. Would there be a more comfortable position to view in? What about the target bullseye pattern? Could there be a better shape or pattern than the one that's there now?

FYI - I'm not a vendor or marketing person and have no association with TelRad. I'm one of those guys who believes if you can't take it apart and change it, it isn't really yours.

#2 Mike in Tampa

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Posted 26 June 2013 - 08:53 PM

it would be nice if it weren't so darn big. there are plenty of red dot finders that take up a lot less space. 1st suggestion to allow for a smaller footprint would be to use the smaller watch style batteries instead of the AA's

#3 bherv

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Posted 26 June 2013 - 08:57 PM

I built a dew heater for mine. Two resistors under the glass with connectors at front. I use a controller for my homemade dew heaters.
Barry

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#4 GetSomeSleep

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Posted 26 June 2013 - 09:02 PM

I was wondering if size was going to come up. I use mine on larger scopes, so I don't notice the size so much. The size also lets me use lithium AA cells that have as much as 3000 mA-hours capacity. The LED in mine uses about 20mA, so that gives me about 150 hours of operating time. If it's flashed, say with a 50% duty cycle, then the operating time doubles. The larger size also gives me space to put in extras like the microcontroller circuit. But, in a commercially made product, you could put the microcontroller in a smaller package.

#5 okieav8r

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Posted 26 June 2013 - 09:26 PM

Here's an article I wrote for Astromart a few years ago regarding an easy little upgrade for the reticle adjustment knobs on the Telrad. It's comprised of valve stem covers, and a dab of both white and glow-in-the-dark paint.

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#6 Monadnock

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Posted 26 June 2013 - 10:07 PM

The method of fastening the valve caps isn't mentioned. I assume it's just a press/friction fit?

Cool mod, BTW.

#7 okieav8r

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Posted 26 June 2013 - 10:16 PM

Yes, on my Telrads, they're a secure press fit. I don't know if there has been much variation on the standard knobs over the the life of the Telrad, but if they don't press on securely, one can probably figure out a way to make them stay on, like a neoprene sleeve or something.

I originally put the valve stem covers on because they were just easier for my clumsy fingers to fiddle with. The idea of making them easier to see came shortly thereafter.

#8 Monadnock

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Posted 27 June 2013 - 09:34 AM

Thanks, Rex. I like the idea.

I actually have numerous strips and dots of glow tape on both my scopes. Tripod legs, edges of my Telrad, hand control "holster", focuser, TDC on my objective covers, eyepiece trays, etc. That was one of my first customization "mods" I made to them. Sure beats knocking the alignment off reaching for the focuser (Dob) or feeling around Ray Charles style for everything. I find myself reaching in my pocket for my red flashlight FAR less frequently with the tape applied.

#9 SteveG

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Posted 27 June 2013 - 01:55 PM

Here's my thread on making a self-contained internal dew heater:
http://www.cloudynig...rd=telescope...

#10 ccs_hello

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Posted 27 June 2013 - 07:55 PM

LED flasher works fine for me. See this CN thread.

Also, hacksaw Telrad description here, if you want to shrink it down a little bit.

Clear Skies!

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#11 Jon Isaacs

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Posted 27 June 2013 - 09:06 PM

it would be nice if it weren't so darn big. there are plenty of red dot finders that take up a lot less space. 1st suggestion to allow for a smaller footprint would be to use the smaller watch style batteries instead of the AA's


I think the fact that they use AA batteries is one of the best things about the Telrad. AAbatteries are cheap, easy to find and last forever. I believe the length allows a linger optical path which is at least partly responsible for the essentially non-existent parallax error as well as the large reticule.

There are plenty of other smaller non-magnifying finders but they do not have the capabilties of telrad. There are good reasons the Telrad is larger than most. Redesigning it so it were smaller would be helpful for some applications but I don't see compromising the capabilities nor the battery life as a positive. Maybe reposition the batteries so they were underneath the optics, that would shorten it.

Jon

#12 GetSomeSleep

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Posted 01 July 2013 - 10:33 PM

The irony about moving the batteries to the underside of the TelRad is that it would add height to the unit which people are paying extra for with the height extenders.

Maybe the best design would be a short unit with the batteries on their own level at the bottom of the unit to give it extra height. I still like the microcontroller flasher/automatic shutdown circuit in mine. You get better flash patterns than the commercial circuit that just flashes on and off and I don't worry if the unit gets bumped on in transit.

#13 Nils Olof Carlin

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Posted 04 July 2013 - 01:00 PM

Finally, I made my own LED flasher from a PIC 12F625 microcontroller. Yes, I know you can buy LED flashers already, but the microcontroller can give you lots of different selectable patterns, including pulse width modulation that brightens and dims a flashing pattern automatically. Plus, the microcontroller has an automatic shutdown after a set time. Wouldn't it be great if your TelRad turned itself off if you forgot to, or the on/off knob got bumped? Mine does and it cost me less than $20 in parts.


In this thread , near the end, I have shown my own solution to flashing. It uses a single CMOS circuit: I push a button, and the blinking starts (approx. 1 blink/second), and goes on for about a minute. When idle, the circuit draws next to no current - forgetting it on won't kill the batteries.

Nils Olof






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