Jeff, K6JCA, kindly sent me a paper, (Dunsmore 1991) which gives design details for a variation of the common resistive Return Loss Bridge design.
This article expands on the discussion at Return Loss Bridge – some important details, exploring Dunsmore’s design.
Above is Figure 3a from (Dunsmore 1991). Continue reading Return Loss Bridge – Dunsmore’s bridge
Fox Flasher MkII and several follow on articles described an animal deterrent based on a Chinese 8051 architecture microcontroller, the STC15F104E.
Fox flasher MkII update 7/2019 documented a rebuild of the enclosure etc.
This is an update after five more years operation outside.
Above is a pic of the device. The polycarbonate case has yellowed a little. Importantly the cheap PVA has not crazed, it is kept dry by the outer enclosure, and a hydrophobic vent helps keeps the interior dry.
The battery is a pouch LiPo single cell, it is in good condition. A previous trial with 18650 LiIon cells showed they were unsuitable for the environmentals.
Radiosonde Auto-RX 1.7.2 is a software package for downloading data from a weather balloon.
Above is a screenshot from Radiosonde Auto-RX 1.7.2. Continue reading Radiosonde Auto-RX 1.7.2 – current consumption capture
In Repack of Hikoki / Hitachi EBM315 battery pack (DB3DL2) I discussed the repack of a battery pack. At the same time I also ordered a no-name replacement 1.5Ah battery on Aliexpress for $25 incl shipping… with some reservation as most batteries I have purchased on Aliexpress have failed to deliver half of the rated capacity.
So, the battery arrived and I tested it, the purple trace above, and I was pleased to see that it exceeded the rated capacity a little.
So, I purchased another from the same seller, and it duly arrived, and to my surprise, it exceeded rated capacity by 30%.
Both batteries recharge properly on the Hitachi / Hikoki charger.
Time will tell whether they are good value. In any event, they use screws to hold the cap on so they can probably be repacked with good cells.
I have had a Hitachi DB3DL2 ‘pencil’ type cordless screwdriver for about 12 years, and one of the supplied two batteries (EBM315 1.5Ah) has just failed. This is not the first failure, the charger failed after about five years use and the LED push button became electrically leaky flattening the battery so the push button was removed. The second battery is still working, but at about 65% capacity.
It is actually a really good tool to use, and so worth trying to extend its life. To that end:
Above is a capacity test of the new Aliexpress 1.5Ah battery and the working 14 year old Hitachi battery. The little squiggles are concerning, to be further investigated. It is my experience that most rechargeable batteries purchased on eBay and Aliexpress grossly fail to meet specified capacity, the one is a welcome change… though note the quite low cell voltage to achieve rated capacity. Continue reading Repack of Hikoki / Hitachi EBM315 battery pack (DB3DL2)
The BN-V12U is a NiMh battery used in JVC video camera / recorders in the 1990s. It was used in a lot of competitors products, and found its way into other applications. In my case, it is used in a Leica T107 theodolite.
This article documents initial tests on two new after market Chinese made batteries purchased on Aliexpress 12/2023 for about $34 for two, incl shipping. These have a label rating them at 2.1Ah. Continue reading Battery testing – BN-V12U
I have a GPSmap 76 which has not been used for perhaps 12 years, stored without batteries.
The GPSmap 76 appears to use an internal battery for non-volatile memory and clock, likely to be a MC621 rechargeable LiIon (MnO2) button cell of about 3mAh capacity. Continue reading Reviving a Garmin GPSmap 76 (GPSmap76)
What’s that… the centre to centre distance is less than the round wire diameter… a physical impossibility… never mind, Google Bard can solve it!
Not only solve it, but warm you with a bit of humanistic chat to lend credibility to its answer.
This is worse than your average online expert on social media! A high tech automaton that is not fit for this purpose?
PS: I hope my doctor does not use Google Bard to recommend my treatments!
Having seen an online expert speaking very positively of Google Bard in solving ferrite cored inductor problems… so I tried it out.
Well, that is encouraging, seems a lift from datasheets and it seems ok at a glance.
Now lets go deeper. Continue reading Google Bard on ferrite cored RF inductor challenge
A ECO-LFP210 10Ah 4S LiFePo4 battery was purchased on eBay for a solar powered project, cost about $65 delivered.
Above, the battery (the Anderson Power Pole connector is an addition). The battery incorporates a battery management system (BMS), so protected against over voltage, undervoltage, over current, and cell balance is preserved. Continue reading Initial review of ECO-LFP210 LiFePo4 (LiFe) battery