low cost spectrometer ish ALTA II tear down

more about it

https://www.lpi.usra.edu/education/products/spectrometer/

my two cents

cheaper to build it yourself and it will probably be just as good

 

neato speaker hack (stereo + bluetooth)

neato robot cleaner

needed to open and fix the side brush

 o-ring dried and failed

and while waiting for the o-ring to arrive

saw an actual speaker instead of just a buzzer

and thought of a nice new upgrade to its boring sound

used some stuff that i already had 

bluetooth module cost about $1

amplifier module cost about $0.25

also added another speaker that i had

speaker resistance should be the same for both sides left / right

lower resistance is better in general

in the case of neato d85 it was 8 ohms 1.5w  2.5cm

quick inspection look like ajt 436 so maybe max 436?

package size is 1x1mm

 

a matching speaker should cost about $0.40 

and small diy job of wire extensions and speaker mounting 

vhm-314

pam8403

current consumption while idling is about 190mw

while playing at full volume consumes around 850mw

although i dont mind if the robot battery wont hold the charge

to complete the full cleaning cycle it might be worth 

to add a small separated battery for the music section

 

and a short video

sounds much better and most importantly

stronger then the boring vacuuming sound

sound and motor test

still get some annoying distortion

need to get a stronger neodymium speakers

the location of the added speaker seems reasonable

and should be facing the middle of the room

as the opposite side housing the side brush

which should face the wall and corners

more photos and videos to be continued

srs sr620 universal time interval counter

 

another ebay find

stanford research sr620

bought it thinking it would be a challenge to fix / repair

which wasn't the case device was fixed within an hour

passing all the tests without a single error

the scrambler (voice) acs-2

another ebay epay find

blaming the customs for the broken handset

fast repair job

movie of the handshake

next step (to be continued) is to reverse engineer

the handshake and voice scrambler for fun

and using only one handset

3d touch sensor tear down

magnetic range sensor with coil

tds3054 oscilloscope 500mhz 5gs/s

 

tds3000 series are all the same (bandwidth is limited by sw)

tds3012, tds3032, tds3052, tds3014, tds3034, tds3054

fixing a dead channel (cold joint)

replacing bad capacitor

some old dried plastics parts broke during the not so intuitive take apart 

 

checking for the first time the scope with dc direct to its battery pins

upper is negative lower is positive