Tony knows this but others might not, the NEC IR protocol uses a address (6-bits) and command (7-bits) structure, so the sender and receiver usually need to use the same address and the receiver must understand what functions must be implemented based on the commands that are sent.
Many moons ago I built a IR remote sender using a Atmel attiny2313, that I can share the source code and schematic but making a nice package is the challenge since I did mine on a protoboard. Also, since I wrote my code in bascom-avr you need that compiler and a programmer too
Many moons ago I built a IR remote sender using a Atmel attiny2313, that I can share the source code and schematic but making a nice package is the challenge since I did mine on a protoboard. Also, since I wrote my code in bascom-avr you need that compiler and a programmer too
Last edited:
Code:
Sender side:
const uchar kbdmatrix[4][4] = {
{'0', '1', '2', '3' },
{'4', '5', '6', '7' },
{'8', '9', 'A', 'B' },
{'C', 'D', 'E', 'F' },
};
Receiver side maps the pressed buttons to defines used:
#define IR_BTN_OK 0x34
#define IR_BTN_MUTE 0x43
#define IR_BTN_BACK 0x38
#define IR_BTN_PWR 0x30
#define IR_BTN_VOL_UP 0x31
#define IR_BTN_VOL_DOWN 0x35
#define IR_BTN_0 0x46
#define IR_BTN_1 0x39
#define IR_BTN_2 0x44
#define IR_BTN_3 0x32
#define IR_BTN_4 0x36
#define IR_BTN_5 0x41
#define IR_BTN_6 0x45
#define IR_BTN_7 0x33
#define IR_BTN_8 0x37
#define IR_BTN_9 0x42A TSOP4438 is used at the receiver side. my nec protocol based sender sends non standard commands! You have to program your own receiver to match my sender...
Last edited:
The MC cartridge Denon DL103 arrived. First test of MC stage was a desaster. The MC circuit based on D.Self MC head amp from his book "Electronics for vinyl" using ZTX951 instead of 2SB737 oscillated like hell. Thanks to Bonsai's excellent summary of MC head amps I added a higher value capacitor from opamp output to inverting input to stop MC coil induced oscillation. About 470p instead of 15p does the job. Have had several days of sound test sessions which showed me the (positive) difference using a MC head instead MM cartridge.
Unfortunately I need to design a new MC preamp hat pcb.
First measurments showed very low noise and a very good SNR and THD - far beyond the vinyl specs. (Ortofon test vinyl has "0 dB" 1kHz test tracks with 0.9 - 1% THD which clearly shows the limits of vinyl and also the myth of "warm vinyl sound" because the distortions are mostly 2nd harmonics).
Stay tuned, more info will follow!
Happy eastereggs!
Hi Tony
Happy Easter to you too and all.
A shame to hear about the circuit oscillation with that specific cartridge. Is this the only type you have tried? Can you reproduce the oscillation with an equivalent source impedance?
Wonder if the fix affects frequency response? Or other performance?
At one time I tried to sim the design, recall I had a problem and gave up on it.
If you have a fix, it works and sounds good otherwise, why make a new design?
That circuits been published many times. Never noticed any revisions. Make you wonder how many have actually built it, tested it with various types of MC cartridges.
Check out the pearl3! Interesting design, what you think? Jfet vs bjt? One member has done a smt version, not sure of testing? Even bonsai’s versions are interesting.
That’s cool to measure thd from a record. Really makes you wonder what’s worse, the vinyl or the speakers and we’re designing our amps wanting < -100dB distortion.
Personally I think vinyl is a waste of time. Tons of reasons why, but no different than using tubes imo. I like the albums more for the graphics, liners, notes etc that got lost with CD, digital for nostalgia reasons, but it’s a lousy medium.
Lots of questions, maybe too many
Take care. Have fun.
PS no Easter eggs, New Zealand lamb is the best we can do. And we drive by a sheep farm all the time.
Happy Easter to you too and all.
A shame to hear about the circuit oscillation with that specific cartridge. Is this the only type you have tried? Can you reproduce the oscillation with an equivalent source impedance?
Wonder if the fix affects frequency response? Or other performance?
At one time I tried to sim the design, recall I had a problem and gave up on it.
If you have a fix, it works and sounds good otherwise, why make a new design?
That circuits been published many times. Never noticed any revisions. Make you wonder how many have actually built it, tested it with various types of MC cartridges.
Check out the pearl3! Interesting design, what you think? Jfet vs bjt? One member has done a smt version, not sure of testing? Even bonsai’s versions are interesting.
That’s cool to measure thd from a record. Really makes you wonder what’s worse, the vinyl or the speakers and we’re designing our amps wanting < -100dB distortion.
Personally I think vinyl is a waste of time. Tons of reasons why, but no different than using tubes imo. I like the albums more for the graphics, liners, notes etc that got lost with CD, digital for nostalgia reasons, but it’s a lousy medium.
Lots of questions, maybe too many
Take care. Have fun.
PS no Easter eggs, New Zealand lamb is the best we can do. And we drive by a sheep farm all the time.
Dear Rick,
the oscillations (~ 250kHz) can be reproduced using a 40uH coil directly attached at input (the cartridge has 38uH and 40R dc resistance).
The oscillation can be reproduced also with a spice simulation. Will upload the sim today...
... but for now I need to search for easter eggs in the garden...
Happy easter to all!
the oscillations (~ 250kHz) can be reproduced using a 40uH coil directly attached at input (the cartridge has 38uH and 40R dc resistance).
The oscillation can be reproduced also with a spice simulation. Will upload the sim today...
... but for now I need to search for easter eggs in the garden...
Happy easter to all!
Voila! Found the easter eggs in the garden, now had time to zip the simulation files ...
If changing C7 from 470p to 15p the oscillation starts.
Removing one or two ZTX951 increases the oscillation frequency ... colpitts osc.?
Changing ZTX951 to 2N4403 the C7 / 15p - no oscillation.
Have fun with simulation, Toni
If changing C7 from 470p to 15p the oscillation starts.
Removing one or two ZTX951 increases the oscillation frequency ... colpitts osc.?
Changing ZTX951 to 2N4403 the C7 / 15p - no oscillation.
Have fun with simulation, Toni
Tony, the rbb’ on the Zetex devices is very low (c 1.5 Ohms) so with a low emitter resistance and any small amount of base capacitance they may oscillate. I can’t find any rbb’ data on the 2N4403, but I suspect it is a bit higher than the Zetex devices and this is why it is not oscillating. One thing you could try is to put one or two ferrite beads in the base leads. Don’t use the solid SMD types as the end to end resistance will ruin your noise performance. You need to use the small hollow ones.
(Very nice looking preamp BTW 👍)
(Very nice looking preamp BTW 👍)
Thanks!
According to "The art of electronics - 3rd edition" p.501 the 2n4403 has Rbb 17 Ohms.
Have tried already using only one ZTX951 with ferrite bead - oscillates with same (relatively low) freq. I don't think that the ztx are oscillating - it is more the interaction of the high Cjc/Cje to the input. The opamp possible interacts with the MC cartridge on input (Cartridge + input capacitor are a form of LC circuit) via the relatively high Cje/Cjc of 3 paralleled ZTX951 (3*1.2n ~ 3.6n/3*290 ~ 900p). Using 2N4403 and adding the capacitors as shown in the picture provokes the same oscillation as ZTX951 ...
Colpitts?
According to "The art of electronics - 3rd edition" p.501 the 2n4403 has Rbb 17 Ohms.
Have tried already using only one ZTX951 with ferrite bead - oscillates with same (relatively low) freq. I don't think that the ztx are oscillating - it is more the interaction of the high Cjc/Cje to the input. The opamp possible interacts with the MC cartridge on input (Cartridge + input capacitor are a form of LC circuit) via the relatively high Cje/Cjc of 3 paralleled ZTX951 (3*1.2n ~ 3.6n/3*290 ~ 900p). Using 2N4403 and adding the capacitors as shown in the picture provokes the same oscillation as ZTX951 ...
Colpitts?
Code:
*ZETEX ZTX951 Spice Model v1.0 Last Revised 27/5/92
*
.MODEL ZTX951 PNP IS=1.3766E-12 NF=1.013 BF=187 IKF=5.0 VAF=66.3
+ISE=1.4E-13 NE=1.41 NR=1.0099 BR=56 IKR=0.9 VAR=33 ISC=1.7E-12
+NC=1.4 RB=0.029 RE=0.020 RC=0.0255 CJC=287E-12 MJC=0.4522
+VJC=0.4956 CJE=1.15E-9 TF=0.83E-9 TR=20E-9
*
*$
*Attachments
Last edited:
Yes, almost certainly a Colpitts oscillator. Just check that the 2N4403 isn’t oscillating at HF. You might be able to quell the oscillation by loading the base to 0V with a 1-2nF cap. Since the source resistance (MC) is low, this will hardly affect freq response. I have not played with the Self circuit - it’s quite interesting.
This tip is working at least in simulation. Changing the 470p cap on input to a 4.7n stops oscillation.
Square wave response has a hefty overshoot but well damped. In combination with C7 e.g. 100p the THD performance is still single ppm up to 20k
The new rev. 1.2 PCB will arrive in about a week or so ... tests will follow!
BR, Toni
Square wave response has a hefty overshoot but well damped. In combination with C7 e.g. 100p the THD performance is still single ppm up to 20k
The new rev. 1.2 PCB will arrive in about a week or so ... tests will follow!
BR, Toni