Technical, Techniques, Hints, and Tips > Radio Equipment
Truly old school Digifleet find.
roycv:
Hi DG I was given a choice too. I went for a multi-focal lens. I can read my car dashboard and glance straight up at motorway signs etc. I am very impressed. I expect to have the other one done in a couple of weeks.
I have my long sight restored to no glasses needed for driving and all the reading elements of old glasses are too strong and was advised to buy some cheap interim glasses for reading. (+2.5).
I am hoping for the best with my right eye which was much stronger than the left when that is done.
Best of luck with options
Roy
chas:
I just had my second eye done last Monday, i was back in the workshop yesterday. I hadn't realised how much extra light i was using to see what i was doing.
Its a fantastic fuss free operation. One thing though, my mate kept putting off going for his op. The result was that he had problems, nothing that cant be sorted, but it will take a while, probably months . I'd encourage anyone who needs it to go asap.
Chas
HMS Invisible:
No-cost lipo migration for Tx.
Replacing the 8.4v hex NiCd in my Fleet Tx with two scavenged vape lipo cells (500mAh/1.85Wh & 156gram lighter) would maintain the same capacity. It's not actually worth me reviving the original pack for re-use. I could see how well it fares on the surge current stage to jump start and to note how many charge-discharge cycles revives original cell capacity. Previous 600/700 mAh welded NiCd Tx packs took two cycles but were not left crusting over for forty years.
Another handy refinement would be a battery state monitor, probably a beeping one rather than the bargraph.
I recommend a led bargraph as an on-board fault finder for those that think they can get away, problem free, with using AA 7.2v NiMh packs or old packs straight from long term storage or if they have never given a thought to internal resistance in a NiMh drive battery.
Test post using PostIMG for 300kB lipo jpeg & 278kB attachment for NiCd then bargraph.
scimitarjohn:
I just use 18650 Li ion batts now, about 6 quid for branded flat tops, the problem with that is that 3.7v multiples make it difficult to achieve some voltages, ie 8.4v. I suspect the 8.4 volts comes from that multiple of 7 and 1.2v Ni cads giving 8.4v, I also suspect the design voltage of the Tx may well have been 9v. 7 Ni cads fully charged and in good nick will easily give you 9v anyway, so that's all safe. So the solution, 3 18650 Lions giving around 11v and a LC7809CV 9v voltage regulator chip, incorporating this into a truly vintage set like the Digifleet should be no problem. As a matter of interest my AM set takes 50-60mA so even on AA dry cells you should get around 20hrs use, the Lions I use should give around 40hrs use! enough to keep most of us in happy boating me thinks.
HMS Invisible:
I'm sure you will find from a bench discharge test that 2s lipo, even the 3.6 nominal type, will always exceed the voltage of a good 7s NiMh or NiCd by virtue of its 4.2volt start point and lower internal resistance. The flat portion of the discharge curve means 3.6 x Ah per cell gives a true watthour rating. I'm currently using up 3.6 Ah 13Wh LG cells (3.6x3.6) in ebike batteries.
I've repaired, tweaked and adapted these discrete component transmitters. I'm certain, even with the cmos oscillator, a Tx designer, forced to use 12.6 volt, would use the better noise rejection of resistor, or resistors, in preference to a transistor & zener regulator of that day. Later FM Txs & Rx's I've seen have so far split their supply using a resistor for the rf section & a regulator for an encoding circuit and only if it is needed. In the case of monolithic encoder chips, like the NE5044 chip in your 40FM Fleet set, most have an inbuilt linear regulator. Without checking, and before the use of processors, I think Futaba and Hitec only used a series drop resistor between the 8s Nixx supply to drop voltage & burn off excess power.
2.4GHz supply
I have a boost regulator somewhere and I'd experiment with a 1s to whatever voltage is needed if I was about to adapt a 2.4GHz radio. That's surely worth you investigating whether Ebay lists a 1s to 9v booster for the 2.4G project. A pen bank's charge/discharge circuit will give 5v at ~ 0.5Amp.
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