26-11-2013, 10:09 AM
Thanks for the helpful info.
Re the age of the project (In RB back in 2003), it only serves to underline the long gestation period of bringing my projects to fruition! I made the PCB for the wobby back in 2009, by which time the varicap diode was hard to get hold of, Toko had stopped making the particular coils, (along with others) and they've since become virtually unobtainable, though last time I checked, Peter at JAB still had a few. I managed to get all four coils from here and there and to get on with it.
I'd almost finished the wobby and made a little comb-jointed oak box for it when someone said he'd made a sawtooth generator to obviate the need to take that from the scope timebase, so I made that, along with a newly designed front panel. The sawtooth jobby used a 555 timer and didn't work. I made another just in caae I'd made a silly mistake and that didn't work either. In the end, it was due to having used an ordinary 555 (as specified) and it only worked when that was substituted for a CMOS 7555.
Then when I checked the coverage of each band of the wobby on my frequency counter, I discovered that the coils for ranges 3 & 4 were transposed due to an error, evident when comparing the circuit (fig 2), with the layout of the PCB (fig 3).
Then I started building the probe and other things took over, so it has languished forgotten for the last 3 years or so.
Then I went to Keith's talk at the recent Golborne Swapmeet, which enthused me to finish the probe, put the wobby to good use and add to my experience.
The wobby uses 2 x PP3s and I'm presently trying to stop myself from incorporating a mains PSU, having found a neat little 18V PSU from a scanner or something. Put it down David - later will do!
When I actually do get round to using the wobby and probe, I'll probably discover that they both work fine, and the only errors that exist are due to my own ineptitude - not in building the wobby and probe - but in my scant technical knowledge on such matters, which has all the depth of a Kleenex tissue! My constructional expertise has always exceeded my technical ability by a large measure.
My problem these days is that having been retired for almost 20 years I'm so very busy and often away from home that I end up dabbling in lots of things and never get sustained chunks of time to see anything through from start to finish in a short time frame. I have erratic bursts of activity, punctuated with diversions into other avenues. Probably undiagnosed ADHD, but I'm not a doctor so I wouldn't know. I've lost count of the number of times my wife (who has elevated to an art form her ability to state the blindingly obvious), has helpfully and sensibly stated: "Might it be a good idea to finish one thing before you start another?" Can't argue with that.
Ho hum - rambling and dribbling again.
Re the age of the project (In RB back in 2003), it only serves to underline the long gestation period of bringing my projects to fruition! I made the PCB for the wobby back in 2009, by which time the varicap diode was hard to get hold of, Toko had stopped making the particular coils, (along with others) and they've since become virtually unobtainable, though last time I checked, Peter at JAB still had a few. I managed to get all four coils from here and there and to get on with it.
I'd almost finished the wobby and made a little comb-jointed oak box for it when someone said he'd made a sawtooth generator to obviate the need to take that from the scope timebase, so I made that, along with a newly designed front panel. The sawtooth jobby used a 555 timer and didn't work. I made another just in caae I'd made a silly mistake and that didn't work either. In the end, it was due to having used an ordinary 555 (as specified) and it only worked when that was substituted for a CMOS 7555.
Then when I checked the coverage of each band of the wobby on my frequency counter, I discovered that the coils for ranges 3 & 4 were transposed due to an error, evident when comparing the circuit (fig 2), with the layout of the PCB (fig 3).
Then I started building the probe and other things took over, so it has languished forgotten for the last 3 years or so.
Then I went to Keith's talk at the recent Golborne Swapmeet, which enthused me to finish the probe, put the wobby to good use and add to my experience.
The wobby uses 2 x PP3s and I'm presently trying to stop myself from incorporating a mains PSU, having found a neat little 18V PSU from a scanner or something. Put it down David - later will do!
When I actually do get round to using the wobby and probe, I'll probably discover that they both work fine, and the only errors that exist are due to my own ineptitude - not in building the wobby and probe - but in my scant technical knowledge on such matters, which has all the depth of a Kleenex tissue! My constructional expertise has always exceeded my technical ability by a large measure.
My problem these days is that having been retired for almost 20 years I'm so very busy and often away from home that I end up dabbling in lots of things and never get sustained chunks of time to see anything through from start to finish in a short time frame. I have erratic bursts of activity, punctuated with diversions into other avenues. Probably undiagnosed ADHD, but I'm not a doctor so I wouldn't know. I've lost count of the number of times my wife (who has elevated to an art form her ability to state the blindingly obvious), has helpfully and sensibly stated: "Might it be a good idea to finish one thing before you start another?" Can't argue with that.
Ho hum - rambling and dribbling again.
Regards, David.
BVWS Member.
G-QRP Club Member 1339.
'I'm in my own little world, but I'm happy, and they know me here'
BVWS Member.
G-QRP Club Member 1339.
'I'm in my own little world, but I'm happy, and they know me here'
