Touchy Circuit..?

[AD7N]

what's the most finicky circuit type you've ever worked on?

"finicky" means tough to tune or ensure proper operation.

[K8ERV]

I can't think of anything more touchy than setting a regen receiver for it's max gain. Just one atom short of oscillation.

TOM K8ERV Montrose Colo

[KO6WB]

When I was servicing communications equipment in the USAF we had one setup that was a data link. It had free running flip-flops that had to be adjusted to be at a certain frequency. This was slight lower in frequency than the temperature controlled main crystal controlled oscillator was running at. You would have to get the frequency of the crystal adjusted to a very tight tolerance. Then you had to get the flip-flop to trigger by the frequency the crystal oscillator. The adjustment was tedious and extremely fussy.
Ahhh,,,the good ole days.
73
Gary

[KE3WD]

But to answer the OP's question:

I'd say "anything Heathkit"....


73

[VK6ZGO]

When I was servicing communications equipment in the USAF we had one setup that was a data link. It had free running flip-flops that had to be adjusted to be at a certain frequency. This was slight lower in frequency than the temperature controlled main crystal controlled oscillator was running at. You would have to get the frequency of the crystal adjusted to a very tight tolerance. Then you had to get the flip-flop to trigger by the frequency the crystal oscillator. The adjustment was tedious and extremely fussy.
Ahhh,,,the good ole days.
73 Gary

That's a bit like some of the old octal tube type TV sync pulse generators where they tried to save tubes by syncing astable multivibrators,so that two tubes could divide by 8 or so times each pair,instead of just having cascaded bistables.
This type were pretty much obsolete,but they had one at the Tech College when I was a kid--total nightmare!

But,my most fiddly would have to be either:

(1) Setting up an Image Orthicon TV camera--you could get them where they looked right,place them in service ,& they would be noisy!
Set up exactly correct they were magnificent!

(2)Converging a "Delta gun" picture tube !

73,VK6ZGO

[AF6LJ]

That's a bit like some of the old octal tube type TV sync pulse generators where they tried to save tubes by syncing astable multivibrators,so that two tubes could divide by 8 or so times each pair,instead of just having cascaded bistables.
This type were pretty much obsolete,but they had one at the Tech College when I was a kid--total nightmare!

But,my most fiddly would have to be either:

(1) Setting up an Image Orthicon TV camera--you could get them where they looked right,place them in service ,& they would be noisy!
Set up exactly correct they were magnificent!

(2)Converging a "Delta gun" picture tube !

73,VK6ZGO

I would have to agree with number two...
I have done it plenty of times to know I am glad they are gone.

[KE3WD]

I can't think of anything more touchy than setting a regen receiver for it's max gain. Just one atom short of oscillation.

TOM K8ERV Montrose Colo

Let's hope you meant, "just one *electron*" there...


73

[G0CWA]

what's the most finicky circuit type you've ever worked on?

Any circuit who's set up instructions say this part is easy to adjust !!! REF. Mr. SOD and/or Mr. Murphy

73 de Nick G0CWA

[WB2WIK]

Back when I was doing design work, my biggest "finnicky" challenge was probably the output stage of a commercial RF signal generator. It had 43 dB gain and had to be "leveled" to within 0.1 dB output (at 20mW output power, or +13 dBm) with less than 1% AM distortion, from 1.6 to 520 MHz.

That was about a one-year project with a lot of trial-and-error.

An almost as agonizing project was building the UHF octave-bandwidth tunable oscillator which couldn't drift more than about 500 Hz per hour at 520 MHz, so the phase locking circuitry would work. It also had to provide equal and linear FM deviation over the one octave range with <0.1% distortion at 1 kHz modulation and 75 kHz deviation. That also took close to a year.

But although it meant many sleepless nights, it was great fun.

[K7ELP]

I build a lot of electronics projects. Some are RF related and a alot are not. I bought a couple of those old time music box motors that played some tunes that my wife really liked. I decided to build her a music box that upon opening the lid one tune would play and then the next one would play. I timed the play time of both the music box motors and they were the same. The motors worked well on about 50mA at 1.5V. I designed a timer with cmos IC's and used a PWM circuit to drop the 9V battery to 3V and then used a resistor to drop the additional 1.5V for the motors. I spent days perfecting the circuit. Everything worked fine on the breadboard, so I transfered the circuitry to solder type proto board. Spent some more time with my woodworking tools to make a small box out of maple hardwood. For some reason I couldn't make a nice looking wooden box. I went to the craft store a bought a nice one of 1/4 the money I had spent on the maple. Put it all together a opened the lid. The second motor started first, was on for about the third of the time then the first motor started and kept going. I corrected a couple of wiring mistakes but it didn't matter it never work right with cmos timing. After a couple more days of fustration I installed a spdt slide switch to control which motor came on, and a lever microswitch near the lid. Works fine.
I cannot recall ever having this much trouble with any rf project.
73
Ned