I Picked up this Makita from a goodwill for cheap, it looked brand new with only a little sawdust on it. I do not have a battery or a charger for it and am not interested in buying them.
I opened it up and ran a couple wires to the battery connections, I added the capacitor because it has trouble starting. I do not think it is my power supply as it can supply 10 amps, and this only draws about 4, but it seems to need a big kick to get it going, the motor seems to get stuck even when I removed it completely from the saw. Whoever owned it before me may have abused it. I also re-lubed it.
I installed a jack in the bottom of the battery compartment for the cable I am using.
This will work just fine for the projects I may have in the future.
A couple years ago when I got in to this hobby, I wanted to free up some bench space taken up by my Dim bulb Tester, a volt meter, variac, and other devices.
I wanted them to fit in a single cabinet. This is the first drawing I did in Autocad 2002. I began collecting the needed parts for it.
The problem was that I could not find a decent cabinet that did not look cheesy or homemade. About a year ago I bought a B&K 1076 TV Analyst from a Goodwill for about $8. I do not ever intend to work on vintage TV's as they take up too much room. So I parted it out. I kept the case but it was only about 6 months ago that I decided to use that for the case. So I redesigned the device to fit in the new case. This was the final design.
Here are most of the parts needed to assemble the device.
The hardest part was obtaining the front panel. Initially I was going to use a side panel from an old computer case, but could not cut the piece I needed out of it and still have it look good. So I called a local sheet metal shop and bought a piece of aluminum cut to the size I needed. I printed the layout on paper at 1:1 scale, then punched the centers of all the holes. I drilled the holes out, or in the case of the larger ones, I used a nibbler and dremel tool.
I painted the piece gloss black.
This is the case to the B&K 1076
It took about 3 days to do the actual assembly, and this is the final result.
I got really bored yesterday so I built an adjustable regulated power supply based on the schematic I posted.
I had been using batteries and battery packs with clip leads to power transistor radios so I needed to build this anyways.
I have a Lambda LP-532-FM Adjustable 40 volt 3 amp regulated power supply, but it is way to big and heavy for my bench.
So I built this:
I built it in about 5 hours from stuff I had floating around my shop:
A project case.
old power cord and strain relief.
A transformer that outputs 28vac.
15 volt dc meter.
2 amp bridge rectifier pulled from some electronic device.
2200uf 50v electrolytic cap.
.1uf 50v film cap.
120 ohm resistor.
5k pot (I did not have a 3k).
LM317T adjustable voltage regulator.
1 amp fuse on the output side of the transformer.
old SPST power switch.
1 tie point.
There is still room for a milliamp meter.
There is a jumper so I can hook in my DMM as a milliamp meter.
maximum voltage output is about 35 volts but I will not be using it
over 12 volts. The el cheapo DC volt meter is pretty accurate.
I checked the heat sink last night while powering my Ray Jefferson
630rdf and noted that it was indeed too small. I rectified that problem
but then broke a lead on the LM317T and had to get a new one this
I think the new heat sink should be more than adequate, no?
I mounted the LM317T to the heatsink with non conductive thermal
material (otherwise the case would have DC voltage on it) it seems to be
working fine and not getting hot.
I bought this several months ago and shotgun recapped it, since almost all the paper caps were split open.
the guy who owned it was a "TRF man" and did not know anything about regenerative radios. whatever.
worked fine for about 5 minutes or so, then started acting up, with
garbled audio and only being able to sort of tune one station, but when
you would stop moving the tuning dial it would lose the station or at
least that's what it sounded like.
Months pass and I let it sit
on a shelf, today I decided to start anew. I went throught the radio and
checked the resistors, replaced a few out of spec. I thought maybe the
problem was with the oscillator so I replaced a 47pf cap related to
that. cleaned the 12sk7 and 12sa7 sockets, freed up a trimmer cap that
was a little rusted. changed out the antenna wires, tried a different
antenna, but nothing really made a difference.
then... I was
going through the radio with my signal tracer, and not really being able
to trace an RF signal I decided to make sure the AF was working, I was
getting the same audio from the signal tracer as I got from the radio,
until I placed the probe on the center pin of the volume control. All of
a sudden I got clear audio from both the signal tracer AND the radio,
AND the tuning started working. If I removed the ground wire of the
signal tracer from the radio chassis and touched the center pin of the
volume pot it went back to the way it was.
I spent most of the day working on it, and after replacing all of the original mica caps, I found that if I placed a resistor to ground in certain places the audio would return. I thought about this for a while and realized that all the components in question went through the volume pot to ground.
I pulled the volume pot and opened it up, this is what I found.
It is hard to tell from the above picture, but the carbon is missing from the last 3/8" of the pot.
I did not think I had one so I took a break and went over to my brothers house for a while.
When I came back I looked though my stash of pots with switches and low and behold I had the exact replacement a 500k pot, with a switch AND a 100k tap.
I installed it and it work fine.
The last problem was that the original speaker was trashed.
I found a usable speaker, drilled the bracket off the back of the old speaker, attached it to the new one and mounted the speaker.
I also made a new mask for the speaker and glued that and the speaker cloth to the speaker.