Tweet
It all seems to working well now. I took some time to try out various mods I have found- mostly on these forums.
One suggestion was to run the osc from the battery 9v. Bad idea. Its a Colpitts - the frequency varies with voltage. As the battery wears the frequency changes. However, mine worked better from 9v. When I investigated I found that the F at 9v was almost spot on, but not at 5v. I fixed that with a 4n7 across C2 (Tesoro circuit ref) and run at 5v. I added 47pf across C12 (another post) and that made a small difference to GB. Hardly worth doing.
Adding a diode from Q5 of IC1 (to D8/9/10), reduces tone f and sounds much better. I liked that one.
I added another 10nf across C25 (my mod) seemed to make it more stable.
Added 20M across the auto switch - because on later models Tesoro does.
ReplaceR66 with a 2k2 connected to the -5v rail ; gives much better setting of sense pot. Nice one.
Op amps.
TL084 Quad works ok, but juicy.
TLO64 Quad, very low I, works ok too.
Strangely, TLC2264 (Quad version of TLC2262) works best. Hmm. But it really does in air tests. Must figure this out....why it is better that is. Especially in disc mode.
Tesoro batt test works fine but I prefer the warning led timer I added to mine.
When first switched on I noticed that after say 30secs, the osc f settles, ie it starts a bit high at first. Well its very coldhere at the moment so I guess this is to do with T1 temp - it passes very little current. It is quite stable.
Going to make a DD coil soon and compare with my concentric. Now these can be made, I have, but they need a lot of care and patience to get right !
My mark1 last year had 6AA inside. I now use one PP3. A lot lighter. Also, the mk1 had to be opened up to change batt.
I am very pleased with the battery compartment I cut into the case (and made with plastic and MEK). Pics in due course. Now I can change the battery easily.
Finally, the mk1 never really worked. I rushed out to a field, found no Romans, (nickels dimes or ring pulls) then threw it in the garage. This time
I spent a lot of time testing and checking (measuring too) and the result is very different.
Hope this was interesting.
One suggestion was to run the osc from the battery 9v. Bad idea. Its a Colpitts - the frequency varies with voltage. As the battery wears the frequency changes. However, mine worked better from 9v. When I investigated I found that the F at 9v was almost spot on, but not at 5v. I fixed that with a 4n7 across C2 (Tesoro circuit ref) and run at 5v. I added 47pf across C12 (another post) and that made a small difference to GB. Hardly worth doing.
Adding a diode from Q5 of IC1 (to D8/9/10), reduces tone f and sounds much better. I liked that one.
I added another 10nf across C25 (my mod) seemed to make it more stable.
Added 20M across the auto switch - because on later models Tesoro does.
ReplaceR66 with a 2k2 connected to the -5v rail ; gives much better setting of sense pot. Nice one.
Op amps.
TL084 Quad works ok, but juicy.
TLO64 Quad, very low I, works ok too.
Strangely, TLC2264 (Quad version of TLC2262) works best. Hmm. But it really does in air tests. Must figure this out....why it is better that is. Especially in disc mode.
Tesoro batt test works fine but I prefer the warning led timer I added to mine.
When first switched on I noticed that after say 30secs, the osc f settles, ie it starts a bit high at first. Well its very coldhere at the moment so I guess this is to do with T1 temp - it passes very little current. It is quite stable.
Going to make a DD coil soon and compare with my concentric. Now these can be made, I have, but they need a lot of care and patience to get right !
My mark1 last year had 6AA inside. I now use one PP3. A lot lighter. Also, the mk1 had to be opened up to change batt.
I am very pleased with the battery compartment I cut into the case (and made with plastic and MEK). Pics in due course. Now I can change the battery easily.
Finally, the mk1 never really worked. I rushed out to a field, found no Romans, (nickels dimes or ring pulls) then threw it in the garage. This time
I spent a lot of time testing and checking (measuring too) and the result is very different.
Hope this was interesting.