Author Topic: getting started with electronics  (Read 47624 times)

Rob.Wilson

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Re: getting started with electronics
« Reply #50 on: July 18, 2010, 06:02:21 PM »
Hi John

Those are the coils in old radios that go around ferrite rods ..................... I Google'd  denco radio coils  :D  ,, you making an old style radio ?

A camera is a must  we like pickeys   :thumbup:

Rob

Offline AdeV

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Re: getting started with electronics
« Reply #51 on: July 18, 2010, 06:14:25 PM »
The way into electronics which worked for me, was through old Electronics magazines (Everyday Electronics, Practical Elecronics, EPE after they merged). Stuff from the late '70s through to probably the late '80s is best, because it's all discrete components; by the time the '90s came around, microprocessors were getting cheap & most projects seem to be either mega amplifiers, or microprocessor based.

Not that there's anything wrong with microprocessor electronics mind! It's just a different type of electronics, is all. And you need to write software, of course...

Biggest problem with electronics projects, in my experience, is having the right components on hand. Faced with a 1000 page Farnell (or RS, or Rapid) catalogue, just what _do_ you buy & what do you ignore?
Cheers!
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Offline John Swift

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Re: getting started with electronics
« Reply #52 on: July 18, 2010, 07:36:39 PM »
Hi Rob ,
            I have made a medium wave  transistor radio with denco coils in the past
later adding a shortwave converter to the mw radio tuned to 1.6MHz
 I would like to have a go with a valve (tube) TRF radio when I have the time

to make the coil former :- drilling a 3/8" dia blind hole in a 1/2" dia 1" long plastic rod ,
 then drilling and tapping  the last part 6BA , for the adjuster , made from  a short ferrite rod or bead glued to a brass 6 BA  screw
the basic former then fastend to a diy 8 pin plug - 8 x 0.1" dia pins spaced around 0.7" circle to fit octal valve base
(being long in the tooth I think in feet and inches but can measure in metric  
I'll use what ever measuring stick is to hand)

I hope it makes sence , I need to find out how to upload jpegs of sketches  without photobucket
« Last Edit: July 19, 2010, 02:57:18 AM by John Swift »

Offline madjackghengis

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Re: getting started with electronics
« Reply #53 on: July 22, 2010, 08:01:25 AM »
Hi and Welcome John  :wave:

i hope to have my fist flux capacitor and photon torpedo up and running next week  :lol: :lol: :lol:  ,,,,,,,,,,,,,,,,, Its coming along slowly at the moment  i am still playing with resistors and capacitors , Ohms law ,, the basics ,,,,,,,, I hope to do allot more this coming winter ,, i have a few projects in mined
 :lol: :lol: :lol:  i thought it was my eyes when looking at the colours  :bang: ,, so i have been checking them with the meter just to make sure ,,, the problem is they are so small and i have to chase them about trying to get hold of them with my sausage fingers ,, then when i drop the dam things i cant fined it,  as they are the same colour as the carpet  :doh:

Thanks for the link and the tips  :thumbup: :thumbup: :thumbup: :thumbup:,,,,,,,,, i have so much to learn  :D


Regards Rob Hi Rob, your best bet is to get new carpet that is a single bland color that isn't the same as any of the components, white is good, but don't walk on it, or it'll get dirty.  All jabs aside, we used to drop components on a painted concrete floor when I worked in an electronics burglar alarm company, and we still had a hard time finding the damned parts.  Just buy parts in bags of ten and plan on finding the ones you drop when you're not looking for them. :lol: mad jack

Do you have any projects on the go at the moment ?



 
 

Offline madjackghengis

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Re: getting started with electronics
« Reply #54 on: July 22, 2010, 08:44:26 AM »
Hi Rob, I've long had a decent stepper motor I picked up on ebay, and I've got an eight inch rotary table which I want to "digitize", as the crude scratches for marks are hard to be accurate with, and I'm waiting on a cutter to mill the cams of the radial engine I'm building, so I thought I'd find a motor drive kit somewhere, and see about making this stepper motor a permanent part of the rotary table.  I worked in electronics for about thirty years too long, never liked it much except the first couple of years when it was all new, and I was building ham radio receivers and transmitters that used tubes, but I got shoved into electronics when I was in the Marines, because I already knew it, and finding a good technician is like finding a good mechanic for your odd and unusual car or tractor.  You don't let go, once found.  I still know my electronics, but most of my knowledge is geared around antique equipment, as my knowledge of tubes was taken advantage of, as tube theory was no longer taught by the time I went into the field, and all our C-130s we used for refueling, were still using electronics from the thirties and forties.  I do know transister theory, and worked with modern electonics, even teaching it while in the Corps, but it's been fifteen years or so since I retired, and I never did really work much with modern electronics, so I'm learning as I go.  Eventually, I will convert my Enco bridgeport clone to CNC, and probably a lathe or two, but I've got some learning to do first.
   I'm focussing on motor drives to start with, I've also got a nice little atlas shaper I use quite a bit, but down feed while cutting is a bit of a pain, and hard to keep an accurate control of depth, and I think a stepper motor would be an easier "fix" than devising a ratchet drive that works with the down feed in all positions and has feed choices.  I've been looking on the web for motor drive kits, and the bug right now is selecting the right one for the motor I already have, but I will be happy to chime in on any other project with  any help I can, since I do have a solid understanding of the field of electronics, I'm just not up to date on all the new parts and pieces - the principles and rules haven't changed though, ohm's law still rules, and the new parts are generally easier to understand as a whole, than were the box of parts necessary to do the same job using discrete components.  Most of your use of resistors and the like are for control of input current or volts, or for shunting feedback to ground, with all the "work" being done by the integrated circuit, which was once made up out of individual parts and thus finiky demanding components that were complementary.  Working on digital equipment is more about logic than electronics theory, and except for power supplies and the like, it's mostly either on or off, which makes digital electronics easier to get into without getting in over your head.
   My intent with the rotary table is a stand alone device with the expectation of getting into more advanced work ending up with converting my mill and lathe at some time, and having to learn how to interface with a computer between now and then, and deal with the programing when it comes up.  I've built a few Vellman kits including a couple of chopper type motor drives and used them, but it makes more sense going with stepper motors and digital electronics today, than just variable speed, which is all I got from the chopper type motor drives.  They are good if all you want is power feed, or movement and are content with a knob to vary the speed, and a switch to start and stop.  I did the kits mostly to get my hands back in and get comfortable with the work again, having left it behind for lots of years.  I will do a build log on the rotary table, and everything else I do until someone says I'm taking up too much space.  Ta ta for now,  :nrocks: mad jack

Offline John Rudd

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Re: getting started with electronics
« Reply #55 on: July 22, 2010, 05:26:07 PM »
Hi Rob ,
            I have made a medium wave  transistor radio with denco coils in the past
later adding a shortwave converter to the mw radio tuned to 1.6MHz
 I would like to have a go with a valve (tube) TRF radio when I have the time

 

Ahhh.Denco coils... ( Clacton on Sea Essex... :clap: )

Reminds me of when I were a lad reading Gilbert Davey's book  'Fun with Radio'.... a single valve trf receiver using a DF91 ( or IT4 if you like)   Happy days...

FWIW, my first ever radio I built was a crystal set that my dad bought me...it needed a soldering iron for assembly..Not deterred by this, I managed to'dry' assemble it and have it work... :clap:
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Offline John Swift

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Re: getting started with electronics
« Reply #56 on: July 22, 2010, 07:07:09 PM »
Hi Jack
         you have not given any details about your stepper motor ,  is it a unipolar or bipolar motor ?
 if you just want to just test the stepper motor out for now
try some thing like the 3187KT bipolar motor driver or 3179KT unipolar motor drive kits from Quasarelectronics.com  
with a simple  ne555 ic  oscillator  providing step pulses ( could be a modified audio signal generator kit )

I'm a few steps behind you ,
I have thought my fist step is to provide a variable speed drive to the lead screw
to get a practical feel for the torque and maximum speed of the stepper motors

 but first I need to get my old ( new to me ) lathe going first  



Hi John ,
                would that be the green octal plug in ones

   those battery radio valves  work ok of 3 or 4   9v batterys  for the HT supply
you can find scans of the old 90v batterys  if you want to make your own



                                John Swift
« Last Edit: July 23, 2010, 04:54:02 AM by John Swift »

Offline kwackers

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Re: getting started with electronics
« Reply #57 on: July 23, 2010, 04:42:13 AM »
Jack, I know you want to make your own - but if it's any help here's one I made earlier...
http://www.cnczone.com/forums/showthread.php?t=47007
There's source in the first post which might help too.


Re: the 90v radio batteries, a few years ago I made one for a guy I knew. Basically just a set of rechargeables and inverter built into the case of an old battery with a socket on the bottom to charge it up. Worked a treat and even losing the space for the inverter it still ran far longer than the original battery.

Offline raynerd

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Re: getting started with electronics
« Reply #58 on: July 23, 2010, 05:36:13 AM »
I converted my 4" vertex using Kwackers divider...it is great -  http://madmodder.net/index.php?topic=2242.0

Offline John Rudd

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Re: getting started with electronics
« Reply #59 on: July 23, 2010, 07:17:49 AM »



Hi John ,
                would that be the green octal plug in ones

   those battery radio valves  work ok of 3 or 4   9v batterys  for the HT supply
you can find scans of the old 90v batterys  if you want to make your own

John Swift

Ummm.I though they used the B9A plug/socket arrangement...? :scratch:
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Offline John Swift

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Re: getting started with electronics
« Reply #60 on: July 23, 2010, 08:46:51 AM »
Hi John ,
they had both types
B9A base   coils  was for transistor circuits , OC44 , OC45 , AF116 etc 
early mullard transistors  use the same number system used on their  valves ( O = no heater , C = triode  )
 
 octal base coils  for valve circuits , but usefull for fets as well

it all comes flooding back






Offline John Swift

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Re: getting started with electronics
« Reply #61 on: July 23, 2010, 09:49:37 AM »
Hi Kwackers and Craynerd ,

thanks for the web links the  info is very usefull

with refrence to testing speed controller boards
the FC250 board looks like a cut down version of the FC350 board on the mini-millers
I will post the FC250 circuit i have traced from the pcb , if some one needs it ( 240v version )

with blown fuses and  a dead controller , try the simple tests I have used on a mini-lathe speed control
« Last Edit: July 23, 2010, 10:55:25 AM by John Swift »

Rob.Wilson

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Re: getting started with electronics
« Reply #62 on: August 01, 2010, 05:06:35 AM »
Hi Mad Jack


Did you fined a driver for your R/T project ,,,,,,,,,,,,,,,,,,,, fitting a stepper to a shaper is a good mix old and new  :med:  :thumbup:


Rob

Offline John Stevenson

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Re: getting started with electronics
« Reply #63 on: August 01, 2010, 05:20:20 AM »
Yabut fitting two steppers to a shaper is real cool.
You fit one to the bed travel, call that X, and one to a rotary table mounted vertically, call that A.

Now stick a 40 degree or 29 degree vee shaped tool in the holder and a disk in the rotab.

Every time the tool retracts you move X and A at the same time, result is you now have one tooth of a spur gear that has been generated into a perfect involute. One 50 pence tool, easily made and sharpened will cut any size gear in that range.

John S.
John Stevenson

Rob.Wilson

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Re: getting started with electronics
« Reply #64 on: August 01, 2010, 05:26:14 AM »
Yabut fitting two steppers to a shaper is real cool.
You fit one to the bed travel, call that X, and one to a rotary table mounted vertically, call that A.

Now stick a 40 degree or 29 degree vee shaped tool in the holder and a disk in the rotab.

Every time the tool retracts you move X and A at the same time, result is you now have one tooth of a spur gear that has been generated into a perfect involute. One 50 pence tool, easily made and sharpened will cut any size gear in that range.

John S.
:med: :med: :med: :med: :smart: :smart: :smart: now there's at thought John  :dremel:

Rob

Offline John Swift

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Re: getting started with electronics
« Reply #65 on: October 17, 2010, 02:00:33 PM »
Hi Rob ,
just incase your interested

In the November EPE magazine (out now) , the  2010 Teach-in series has just started

Decembers issue out 11 November will have a 12v motor speed control / lamp dimmer

the PDF magazine can be downloaded via epemag3.com (12 issues for $19-99)



for now I,ll have to stop the mods to my lathe and use it !!!!!

I,ve made a few mistakes like removing the old bearings before I had received the new roller bearings
  and had to re assemble it to make some new spacers !!


the last test comfirmed I can now part off without the workpeice trying to climb onto the tool

          John


Rob.Wilson

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Re: getting started with electronics
« Reply #66 on: October 17, 2010, 02:24:09 PM »
Hi John

 
Thanks for the heads up ,,, i will have a look  :thumbup:

Its starting to get cold so working in the warm is starting to look good now  :lol:


Good to here you have the lathe sorted  :dremel:  now what you going to make  :poke: :poke: :D

Rob

Offline madjackghengis

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Re: getting started with electronics
« Reply #67 on: October 29, 2010, 09:46:32 AM »
Rob, I had the same notion with some wiper motors from surplus, I built a couple of the Vellman kits, both worked real well, were good designs, and easy to build.  As was said above, all you need is a 25 watt soldering iron, some good solder, find the 63/37 tin-lead alloy, it's much the best, and sixteenth inch is the size you want for electronics, and keeping the iron tip clean while soldering, and dripping solder while not is of the utmost importance in the life of your iron.  I use a light dimmer switch built into an electrical box meant for four sockets, and use a cover with two sockets and the other half has a slot for a switch.  I cut the connection between the two sockets on one side, so one socket is full wall voltage, and have the light dimmer switch controlling the other socket, so you can reduce the heat on the iron, they tend to be hotter than necessary, and will burn through tips if they are not regulated.  It's a lot cheaper than buying a "regulated soldering iron" which can cost well over a hundred bucks here, I don't know what that translates to there, but I bet it's too much there too.  a cheap cellulose sponge, kept damp in a jar lid, is good for wiping off the tip just before soldering, and cleaning off the burnt flux after soldering, before retinning, and setting it aside.  I keep a roll of eighth inch solder just for tinning the tip, to save the good stuff for the board.  I hope this helps you pick out the cheap stuff, and get a good job done with it. :poke: mad jack

Offline John Swift

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Re: getting started with electronics
« Reply #68 on: October 29, 2010, 11:11:53 AM »
Hi Madjack ,

I agree with you

velleman kits are good
the pcb's with the solder resist layer are easy to solder
back in 2002 , I built the K7105 lcd 'scope that worked first time

a long time ago I built a very simple soldering Iron saver
 an idea in a 1970's copy of "practical wireless" i think

using a modified switched socket
a 1N4004 diode across the switch kept the iron warm (on halfwave dc )
closing the switch the iron rapidly heated up

regulated iron are a bit expensive for hobby use
the weller wtcp 50 I have is about £ 140 now
most of the time I use a 18w antex iron and 0.7mm 60 /40 solder


    John





Offline AdeV

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Re: getting started with electronics
« Reply #69 on: October 29, 2010, 01:47:19 PM »
John,

If you don't mind Chinese tools, Farnell do a range of very cheap soldering stations: http://uk.farnell.com/duratool/1296771-5090726-1467280/kit-soldering-st-wire-cleaner-uk/dp/1737234

I bought two of those (because they were so cheap) and some spare parts, only used one of them so far & very happy with it!
Cheers!
Ade.
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Offline John Swift

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Re: getting started with electronics
« Reply #70 on: October 29, 2010, 02:19:06 PM »
Hi Ade ,

looks good

if i didn't have the weller iron all ready

I would be tempted , the 1mm and 3mm bits it will do most of the jobs I do

with 2 irons you can use one for lead / tin solder and the other for the hard to use lead free !

Antex do bits for SMT work thats not too expensive

not that I get much practice , to need them just yet

   John