- Joined
- Jan 8, 2012
- Messages
- 7
Combination of my woodworking coupled with some brass parts made with my new lathe. Wood is Jatoba. Black plastic is delrin.
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Loose Coupler Crystal Radio
- Thread starter markbxr400
- Start date
- Joined
- Jun 23, 2011
- Messages
- 786
Absolutely beautiful!!!! Have you hooked it up yet? What kind of "loose crystal?" Galena? What did you use for a Cat's Whisker? Can you take more photos? I'd love to make one!!!
John
- Joined
- Jan 8, 2012
- Messages
- 7
Yes, galena crystal (I have a huge rock that I chip pieces off of and set in a melted chunk of solder in a home-made cup).
I'll provide a few pics and also show you what a scavenger I am and how I find stuff that is close and make it into what I need. The plumbing and lamp part sections of your local harware store is your greatest friend.
Base:
The base is 13" x 6" x 3/4" Jatoba with a simple raduis beveled edge (I believe 3/8" round router bit). The black base that sits on top of this is a 12" x 5" x 1/4" piece of delrin with a fancier routed edge. Delrin machines very nicely with woodworking tools, and doesn't melt as easy as plastic.
You'll see in one of the later pics that I routed channels underneath the base to route my wiring so that everything is clean up top.
Coils:
Outer primary coil is 3" phenolic tube (CE) that is 5" long. I wound 138 turns of 22 gauge magnet wire, which made it about 800 microhenries.
Inner secondary coil is 2-1/4" phenolid tube (CE) also 5" long. I wound 180 turns of 24 gauge magnet wire, also making it about 800 microhenries. I tapped this coil every half inch. I used some wood stain to try to get the tubes to match the jatoba wood. Once coils were wound on the tubes, I sprayed about 5 coats of high gloss polyurethane over the whole thing. This helps to keep the windings firmly bonded to the coil tubes.
By the way, you can order the Delrin and the phenolic tube (linen or canvass, LE or CE) from Boedeker Plastics in Shiner, TX (you can get their phone number and email off their website)
More writeup in next thread.
Mark
I'll provide a few pics and also show you what a scavenger I am and how I find stuff that is close and make it into what I need. The plumbing and lamp part sections of your local harware store is your greatest friend.
Base:
The base is 13" x 6" x 3/4" Jatoba with a simple raduis beveled edge (I believe 3/8" round router bit). The black base that sits on top of this is a 12" x 5" x 1/4" piece of delrin with a fancier routed edge. Delrin machines very nicely with woodworking tools, and doesn't melt as easy as plastic.
You'll see in one of the later pics that I routed channels underneath the base to route my wiring so that everything is clean up top.
Coils:
Outer primary coil is 3" phenolic tube (CE) that is 5" long. I wound 138 turns of 22 gauge magnet wire, which made it about 800 microhenries.
Inner secondary coil is 2-1/4" phenolid tube (CE) also 5" long. I wound 180 turns of 24 gauge magnet wire, also making it about 800 microhenries. I tapped this coil every half inch. I used some wood stain to try to get the tubes to match the jatoba wood. Once coils were wound on the tubes, I sprayed about 5 coats of high gloss polyurethane over the whole thing. This helps to keep the windings firmly bonded to the coil tubes.
By the way, you can order the Delrin and the phenolic tube (linen or canvass, LE or CE) from Boedeker Plastics in Shiner, TX (you can get their phone number and email off their website)
More writeup in next thread.
Mark
Last edited:
- Joined
- Jan 8, 2012
- Messages
- 7
Switching arrangement and slides for secondary coil:
The secondary coil has two 1/4" brass rods, tapped with 8-32 taps on both ends. I used 1/4" phenolic spacers from my local electronic store as insulators (one end of upper rod, opposite end of lower rod). The circuit actually uses each of the 4 upright posts (two long ones on each end, and the two short ones underneath the primary coil).
The upper rod slides through a 3/8" x 6" brass plumbing nipple that is threaded on both ends straight from the hardware store. The two end caps (delrin on hidden end, jatoba on visible end) are held onto the coil tube by this nipple. Hidden (Inside) end has a spring, some mylar washers and a nut. The visible end uses a series of brass lamp parts from the bins at my hardware store (see pic). I machined these three parts simply to shorten the combination to fit on the length of nipple. The switch is cut from a piece of 3/16" brass plate and is sandwiched between fittings on the nipple. The switch contacts are simply 8-32 brass screws.
Sliders:
The two square rod sliders on the primary coil are comprised of a solid 3/16" square brass rod, a 1/4" piece of square brass tube (K&S no. 155), a piece of 3/16" flat springy metal that fits through the square brass tube (and shaped to ride on the coil as shown), a wooden dowel and small #2 brass screw. Drill a 3/16" hole on one side of the small slider, and a very small hole in the other side for the screw to hold the dowel on. Don't forget to sand a strip of the insulation off the coil wire so the sliders can make contact with the coil.
Detector:
The detector is made up mainly of some brass stuff used for a sheetrock texture sprayer (Wal-board Tools cat#50-040). I used 2 of the 4 fittings. What;s cool is the other two can be used for a different type detector I used on another set. The parts go for about $11. However, I happened to find more than a dozen packs of these being cleared out at my local Dollar store for, you guessed it - $1 a pack. I cleaned them out. The clear tube is just plastic, and is 1" diameter, 2" long. I bought it in the fish section of Petsmart - is used in aquariums. The detector supports are some kind of hanger you can also pick up at the hardware store, and simply bent 90 degrees to mount to the base. The galena crystal holder is a small plumbing brass nut that I turned from octagon shape to round. I slid a 8-32 screw through the base from the inside, then poured my melted solder and set my galena crystal. The screw end then goes through one of the brass texture sprayer parts, and then is held on by a round brass ball that is threaded halfway through (also available from the lamp section of your hardware store). The lever that holds the catwisker is just an 8-32 brass screw that I cut the head off and then turned some of the threads off and pointed the end. It has a small thumbscrew hand screwed on, and is threaded all the way through another tapped brass ball. I took one of the lamp balls described abovem finished the partial hole and finished tapping it. Use a piece of phosphor bronze guitar string wrapped on the pointed end of the lever with a pig tail hanging off for your catwisker. The whole thing is simply held together by the balls pressing between the indentions of the texture sprayer parts and the brackets.
Binding posts:
The binding posts were turned from 3/8" brass rod - see diagram. I purchased a ton of 8-32 knurled thumbscrews from a lamp store on the web for about 35 cents each.
The radio works about as expected through a set of high impedence (2000 ore greater ohms) vintage headphones, and using a longwire antenna and suitable ground. You can buy the headphones off eBay for about $10.
I leave it here for now. If anyone has any specific questions, let me know.
Mark
The secondary coil has two 1/4" brass rods, tapped with 8-32 taps on both ends. I used 1/4" phenolic spacers from my local electronic store as insulators (one end of upper rod, opposite end of lower rod). The circuit actually uses each of the 4 upright posts (two long ones on each end, and the two short ones underneath the primary coil).
The upper rod slides through a 3/8" x 6" brass plumbing nipple that is threaded on both ends straight from the hardware store. The two end caps (delrin on hidden end, jatoba on visible end) are held onto the coil tube by this nipple. Hidden (Inside) end has a spring, some mylar washers and a nut. The visible end uses a series of brass lamp parts from the bins at my hardware store (see pic). I machined these three parts simply to shorten the combination to fit on the length of nipple. The switch is cut from a piece of 3/16" brass plate and is sandwiched between fittings on the nipple. The switch contacts are simply 8-32 brass screws.
Sliders:
The two square rod sliders on the primary coil are comprised of a solid 3/16" square brass rod, a 1/4" piece of square brass tube (K&S no. 155), a piece of 3/16" flat springy metal that fits through the square brass tube (and shaped to ride on the coil as shown), a wooden dowel and small #2 brass screw. Drill a 3/16" hole on one side of the small slider, and a very small hole in the other side for the screw to hold the dowel on. Don't forget to sand a strip of the insulation off the coil wire so the sliders can make contact with the coil.
Detector:
The detector is made up mainly of some brass stuff used for a sheetrock texture sprayer (Wal-board Tools cat#50-040). I used 2 of the 4 fittings. What;s cool is the other two can be used for a different type detector I used on another set. The parts go for about $11. However, I happened to find more than a dozen packs of these being cleared out at my local Dollar store for, you guessed it - $1 a pack. I cleaned them out. The clear tube is just plastic, and is 1" diameter, 2" long. I bought it in the fish section of Petsmart - is used in aquariums. The detector supports are some kind of hanger you can also pick up at the hardware store, and simply bent 90 degrees to mount to the base. The galena crystal holder is a small plumbing brass nut that I turned from octagon shape to round. I slid a 8-32 screw through the base from the inside, then poured my melted solder and set my galena crystal. The screw end then goes through one of the brass texture sprayer parts, and then is held on by a round brass ball that is threaded halfway through (also available from the lamp section of your hardware store). The lever that holds the catwisker is just an 8-32 brass screw that I cut the head off and then turned some of the threads off and pointed the end. It has a small thumbscrew hand screwed on, and is threaded all the way through another tapped brass ball. I took one of the lamp balls described abovem finished the partial hole and finished tapping it. Use a piece of phosphor bronze guitar string wrapped on the pointed end of the lever with a pig tail hanging off for your catwisker. The whole thing is simply held together by the balls pressing between the indentions of the texture sprayer parts and the brackets.
Binding posts:
The binding posts were turned from 3/8" brass rod - see diagram. I purchased a ton of 8-32 knurled thumbscrews from a lamp store on the web for about 35 cents each.
The radio works about as expected through a set of high impedence (2000 ore greater ohms) vintage headphones, and using a longwire antenna and suitable ground. You can buy the headphones off eBay for about $10.
I leave it here for now. If anyone has any specific questions, let me know.
Mark
Last edited:
