RGB-led fan ''speedometer''

Title says it pretty much all. Basic idea is the same as previous fan pwm/speedometer control, but rgb led needed bit different approach. all i needed was RGB colours, not all colours what are available, neither colours on the same time. So, i used window comparator circuit to sense voltage levels low/medium/high, and chose led colours RGB in that order. This circuit doesn't have hysteresis connected, i was lazy to add it to his design. But hey, it works :D

Recycling: BROKEN file/folder/map.

Well, the title may be bit confusing, i dont tell about recycling paper files/folders, but instead, i thought it would be good to share this info, if someone is interested .
So, i found that my loved paper file/folder (what is it called anyways in english, book-like thing you put papers inside to keep them organized?) decided to break apart. Nothing big, but the mechanism bended over, so it didn't serve well anymore. Normal people would throw it away, and buy a new one. But what i did, thought a moment, ''any further use for this?'' and bingo, i took it more apart, salvaged; couple stiff enough cardboard pieces to be used as cutting/drawing board, not smooth thought. Handle that shuts mechanism, would make great bended chisel, only needs handle and sharpening. And small bars where you put papers, make good clothes or other hangers, only threads needed and base to install them. YES i may sound bit cheap about all this .

Found from local recycling center: yet another electric typewriter

Due to nice weather, i decided to take little tour to local recycling center, havent been there a while. It seems it was indeed worth it, as i bought another typewriter, AEG olympia mastertype 100i, for 5 euros. Last one was indeed great find, and as it turns out, this was too, even better. And, in WORKING condition.

Last on had safety-earth, this didn't have such luxuries, but there are no metal parts much to be earthed either, so 230v socket was euro-style, 2-pin.
Power boards transformer has much more windings, and ffiltering caps are same brand as earlier, also, fuses of course. control board has 74 family logics, motor control IC:s, couple memories and cpu's of some sort, lockable mini-ide connectors, power resistors and discrete components. PCB at ink cassette assembly has bunch of connectors, opto-coupler plus power resistors & lockable mini-ide connector. Couple more opto-couplers were found at ink cassette too, and paper roll has one too. Again, solenoid took care of letter-punching.
Keyboard has couple IC:s, 74 family, and 5451 led display driver, plus discrete components.

Repair: 12v tower fan. Teardown also

My tower fan stopped working, so i figured i should take a look at it. it was surpsing hard to open in the end, but was made possible, nothing broke up.

Repair itself: At first, nothing really showed up, no bulged caps or anything else sucpicious at first. I measured the voltage pins for transformer, and it turned up to be okay. Then, when i plugged it, somewhat bigger spark came from dc-socket. I measured supply voltage pins for controller chip, 5v as datasheet says, so at least it gets supply voltage. After that, i realized that couple of smd-transistor were pretty warm, hot actually, so i measured them just to make sure they are not SC/OC, they turned out to be just fine. But, then i felt AHA, when i saw possible fault. One of the caps leads were left too long, and it was bent over to wrong place, causing SC. No wonder there was spark at dc-socket. I snipped feet smaller, and 'voila, repair success. Also, i noticed couple bad solderings, which i repair too. Well, i guess made-in-china says it all, but why it worked before just fine?.

But, i took photos also, so here comes teardown:

Inside was 12v brushless fan, and some cind of synchronous 12v motor, for pendulum movement. Pushbuttons for speed adjustment at 3 steps, pendulum on/off, and main power.
The ''brains'' are HT46R47 battery charger controller. Funny, this is fan, not a battery charger, but as it turned out, this controller has PWM output, so nothing strange there after all . I played around a bit when i was measuring the output waveform of PWM pin, and yes it indeed changed duty cycle as speed changed. I also stress-tested system too, by braking the fan, and controller responced by increasing duty cycle. Also, i found out that 1/10x at scope probe really matters, when i measured at x1 position, the was more noice, and fan shutted off. At x10, no problem.

Fan Speed controller with ''speedmeter''

Just simple circuit, but i found it quite entertaining and educating to do, figured it would make good post too.
So, idea is simple: Fan speed controller with ''speedmeter''. Fan is basic 12VDC computer fan without PWM I/O pins, only +/- wires. But it's still controlled with PWM fashion, made my 40106 schmitt trigger, connected as variable PWM controller. At alone, this isn't strong enough to drive fan, so N-fet, IRF540, takes care of this. Also, fet has necessary pulldown resistor on its gate, to shut it down during off-time.

Next stage is ''speedmeter''. Actually, it isn't speedmeter straightforward, but duty-cycle meter. First, there is low-pass filter, along with opamp,lm358 which converts PWM/frequency to voltage, cind of DAC (digital-to-analog?). After that, analog signal is fed to led-driver opamp, i used lm324 quad, which acts as comparator, different levels to different leds.

That's pretty much all to it, feel free to comment! .

scope settings were 10μs/div and 5v/div.

A new piece of equipment to lab. GW GFG-8020G Function generator

Hi, because schools electric lab moves to different place, they cant take all stuff with them. So teacher gave me this function generator because my lab lacked proper function generator. it works like charm, no need for repairs or anything .

it has sine/triangle/square wave, adjustable from 0.2hz to 2Mhz, 1/10/100/1k/10k/100k/1M push buttons set range. voltage depending from load from 10-20v. output impedance is 50Ω
connector are BNC with shell connected to safety ground. Connectors consists of: input VCF, output TTL/CMOS(both only square wave) and normal 50Ω output.
Dc offset +10 to -10, +5 to -5v @50Ω load. attenuation -20db is selected form amplitude switch.
And their adjustment knobs, with pullout switching between features.
Case is held in place by 4 screws from bottom. Back panel has only connector to mains cord. See photos for interior, what i like about interior is that there are no SMD, just personal opinion. I did find user's manual, but if someone has/finds SERVICE manual, i would appreciate it.
comments welcome!

Flea market findings

Just an update of my flea market visit:
well as usual, i went to flea market to test my luck. at first, nothing really caught my eye, but i did find computer PS/2 mises, both ball and analog models dirt cheap IMO, 0.5 € (50 cents) per unit!. considering what is inside of single mise; micro switches, cables, opto-components and maybe some other things, not bad find. Well i took all of 'em, total of 12 pcs. Also, i found 4w/230v fluorescent night lamb at 2€, but its lamp is broken . Inside of lamp was |/0/|| selection rocker switch, and surprisingly, control/ignition board. Board consists basic electricity stuff, mains fuse, caps and stuff. There were also couple nice details also, like NE555 timer, probably for PWM modulation of some sort, and TRIAC Motorola AC97AB.
And wirewound resistor 10w/100Ω. For now, diode on board is mystery, is it light-sensing diode? board has marking CDS on it.

I took photos from fluorescent lamp, and made schematic, if you find any shocking error at schematic, please, go ahead and tell . and sorry if schem. is hard to understand, i dont have that good software and i lack experience in reverse-engineering skills....
and for such amount of mises, i'm not going to make schematics or teardowns . i just find 0.5€/mise dirt cheap, so that's why i posted, if someone wonders why on earth i posted this.

Trio AG-202A audio generator

This time i'll write about Trio AG-220A audio generator, which i use as signal generator, as i lack proper signal/waveform generator. I got this one from school, for free .
This has sine/square wave output, 0/20/40db attenuation which all are selected from slide switches. Output magnitude is about 14VPP at sine, little bit lower at square, as it supposed to be, if I'm not terribly wrong. Square wave also has slight distortion at very low/high frequency.

Power switch is slide switch too, accompanied with orange power on light. Maximum frequency is about 200khz. Frequency is set from rotary switch, which has x1/x10/x100/x1000 prefixes. Final adjustment is made by rotary knob, which is also wired by momentum to bigger wheel, which is analog needle meter along with axis to variable capacitor . This is pretty nice looking to me, I'm old fashioned and i like this type of meter compared to digital, but both has pros/cons but let's not talk about that now. You notice the output magnitude knob is different to others, this is because i had to replace the original one.

Connectors are standard screw-type 4mm banana jacks with hole to wire, and other is chassis ground. Output impedance is 600Ω (ohms)
Back panel has 4mm connectors for chassis ground and SYNC INPUT, for calibration maybe? There are also couple places for screws, their purpose is also mystery, mounting perhaps?.

And traditional metallic name-plate is also found, says model#, seller, etc....and selling date is 19 October 1979, so this has to be at least older than that. Also, this is Made in Japan, well good quality so far.

Metal case is hold by 6 PH1 metric screws, and it opens easily. Carrying handle is also well mounted, with PH2 metric screws.

Now the inside:

None IC's were used, all components are discrete, resistors, transistor caps and stuff. transformer is small, but what is strange IMO is that live/neutral dont go straight to transformer, and its windings has 3 wired other side, and 4 wires other side. I didn't reverse-engineer it or have any schematics so i cant say anything about transformer or anything else's topology Also, there are no connectors inside, all are soldered, but without isolation of any cind like heat-shrink/hot glue. Mains fuse is on neutral side, not on live. Earth is also soldered to chassis.

But, again nice find, build quality was good and interior was interesting.

Comments welcome!

Telecom device Televa RKL-203 found from local auction

Hey all, again nice find from local auction: some cind of telephone-connection/''router''. sorry, i don't know what is it in English ;D. but, here's the photos of it, feel free to comment.
and, why i bought it? just for curiosity/education, and the fact it was only about 20€ so not bad, considering good box, toggle switches etc....
the model is Televa RKL-203. Nameplate says also: REK-testing device, raw translation
There are none IC's used, all are discrete components. numeric rotational switch needs bit oil, or its spring is just stuck/dull. Relays probably use 48v, suggested in forums. I haven't tested this device yet, i have no idea how, but i think its pretty obsolete to use anyway.