Simple Offroad : to the beach ... !!

Got a chance to drive this little Lj80 with my family to the beach. I was expecting to struggle dry sand, prepared some manual recovery gear, but found wet sand instead. Wet sand feels firm, solid, there was no deep wheel print on the sand indicating we are floating on it. Or is this because the feather-weight jimny?

235/70 AT r15 on self painted 15x7 wheel at 20psi walk nicely on the sand. I was carrying air pump incase i need to air-down but not used, seeing how easy it run.

I was using 4wd-high at 1st gear, throttle medium-high constantly while zipping thru the wet sand next to sea water. It was fun, until when we werr about goibg home, there is transition from wet to dry sand which bogged the engine a little, changed to 4wd-low at high throttle easily clear up that area. 

It was fun ride with this little LJ80

Simple Adventure : Backyard trailing

Testing the new LJ...

Simple Offroad : LJ80V 1981 !

And the adventure begins !

Simple edc : Opinel #7 Inox

Just given a new opinel 7 by my father in law, this is my first time handling this unique knife. I spent a week with this knife alone, thus i get few thing to note (for my review) :

- the blade is hard to be open/close => this raise a concern that i need to use too much force to do it, therefore there is chance to danger my hand if it slips. (I CUT my hand twice just open/closing the blade within this week).

- the lock-ring is super tight to turn. It creates mark/bump in my thumb.

- the back edge of the knife is rough, uncomfortable.

- the wood swell in water. This knife shouldn't be use "outdoor" in humid/wet environtment.

- the sharp edge grinded only one side, or just grinded unevenly?

- the blade is thin, flat grind, i think it is more of kitchen blade, which is good for those kind of cutting.

- the does the work to lock the blade.

- inox, kind of victorinox, rust resistance, edge wear not that great but easy to resharpen.

I like the "unique" value. But i can't stand the negative points above. Therefore i disassembled the knife, sandpaper the inner wall to free the blade movement, bend out the lockring (loosen up the lock) and sandpaper the back edge to make it smooth. Now it works better!

Revisiting old friend, the Merrill !

Wide open at minimum focus...

I need no other camera anymore !

Let it Glow #2

How hot is a class A pentode?

As pictured, it is 6n14p pentode at 12.5 watt dissipation, class A biased at 50mA/250Vplate. It can reach 200 degree CELCIUS inside (cathode) !!!

Outside, there is still glass cover and vacuum in between, so the heat transfered may only be the radiated one.

How hot is the glass tube? I have no idea, but smelling the heat on the air surrounding it, well, just DO NOT touch.

Let it glow..

Let it Glow !!

I learned tube circuit the hardest way, by using 6n2p-ev (high gain dual triode, 6.3v heater) at 12V. 

Why is it the hardest, because at 12v, the "tube theory" doesn't work at all :

- biasing is hard, no negative power supply, very small anode current for cathode resistor

- gain is limited, i got only 10 from

- headroom is limited, i lost around 2V on both side, makes only 8v room to play

- output inpedance still very high

On the good side, the limited gain works enough for line level amplification for a small watt application (headphone amp, etc), therefore i build my first "tube amp" for headphone amp.

My headphone had only 16-32ohn impedance, it need current driver more than voltage amplification. Well, such current can't be provided from tube circuit at low voltage supply. Therefore i use BUF634 chip for the output. The tube act as voltage amplification, the buffer act as current driver. 

6n2p-ev is dual triode high gain (similar to 12ax7 but with 6.3v heater), the biasing is done by resistor to positive 12v (??, amazing discoveries by the person who created attached pdf file) to make sure anode voltage at around 6v-7v, with stereo 100kohm pot at input side as gain control, 100kohm plate resistor, 15kohm grid stopper resistor, and buffer at output side (coupled by 2200uf 16v , grounded with 1kohm resistor) to the headphone. This makes me have to wait for the capacitor to fill up (to make sure output at ground level) before i connect the headphone or else loud pop exist, the same need to be done in reverse when power off, headphone need to be removed before power being turned off.

The heater is powered by lm317 set to 6.3V output, slow start done by adding big capacitor at adjust pin to ground, the problem is it waste a lot of power on thr lm317, proper heatsink is needed (300mA x 5.7V, around 2 watt).

The sound is warm, i believe i hear more detail of the sound (like breath of the singer, detailed drum playing), and this save my flac player battery as i can play it at low volume and let the tube amplify.

Let it glow..