thanks salas, for your reply, thats the problem, i think, because i need 3.3V for the interface, as far as i know... 🙁 so it has to be a reflector...
best, horst
best, horst
Thank you for answer!
And it is very interesting: what must be done for adjustment UltraBib for 3.3 or even 1.2 V?
To use a TTL level Mosfet for M2 of low Vgs (th) like the one in Reflektor, to use one LED only by shorting the other, to use 5mA IDSS J3 so to have lowest Vgs (off). That is for 3.3V. For 1.2V only the L-Adapter can possibly reach so low.
I use 1.3 with JLsounds USB to i2s converter at 5V with good results. So if has no real benefit to move to Reflector D, right?
What is replacement for BC560C/BC550C becuse this is now obsolete part. Mouser or Farnell does not stock these.
Can we replace with KSA992/KSC1815? (Different pinout)
Can we replace with KSA992/KSC1815? (Different pinout)
Probably yes but I haven't used them. Look with the scope that there are no oscillations in the Vout rail. If stable with those transistors, it will be OK. (KSC1845 is the KSA992 complement).
*BC550C is still available. For obsoleted BC560C the BC559C or B can be used instead in up to 30V output. BC556B for 31V-45V output.
Hi,
I need some help for troubleshooting. I built an UltraBiB v1.3 minikit positive regulator, I used 9VAC transformer, and I would like using it 5V DC Out. R1 resistor is 4.9Ohm, because my DAC Imax is 26mA. I used 100Ohm load resistor. I started to set the output voltage with the pot. the output voltage was constantly 11.36V independently from the position of the potmeter.
I've installed all fet-s, and transistor to the correct location and orientation, I double checked it. I've also double checked all resistors. Everything looks correct, but it looks like something wrong. Could somebody give me tips where should I start the measurement and the troubleshooting?
Thanks Laszlo
I need some help for troubleshooting. I built an UltraBiB v1.3 minikit positive regulator, I used 9VAC transformer, and I would like using it 5V DC Out. R1 resistor is 4.9Ohm, because my DAC Imax is 26mA. I used 100Ohm load resistor. I started to set the output voltage with the pot. the output voltage was constantly 11.36V independently from the position of the potmeter.
I've installed all fet-s, and transistor to the correct location and orientation, I double checked it. I've also double checked all resistors. Everything looks correct, but it looks like something wrong. Could somebody give me tips where should I start the measurement and the troubleshooting?
Thanks Laszlo
You may measure R1 across its two pins no need to measure each pin across gnd. Anyway 0.55V/4.9R=112mA CCS. So the M1 block works. See Vbe for Q2 & Q3 next.
Do you mean voltage between emitter and base? It is strange Q2 is more stable voltage between emitter and bas is around 200mV but Q3 somethime I measured 200mV but sometimes 2.4V, sometimes I can't read, because always changing.
Yes, Vbe. That should be stable. Between 0.5-0.6V DC in this case. Are you sure about Q2 Q3 types are the right PNP ones?
Remember its pins are CBE from left to right flat face. You measure between B-E. Unload the output and confirm the load resistor's value. Then measure Vgs for M1 & M2 (3-6V pins 1,3). Yes, replace Q2 and/or Q3 if Vbe is still wrong after those other checks.
Before doing semiconductors replacements lastly check the trimmer also with an Ohm meter between pins 1,3 when the power is off. It should be spanning a big range from zero to near its kΩ value (VR//VRR). It needs to be set very low near zero side for 5V out. Did you turn it down enough?
Before doing semiconductors replacements lastly check the trimmer also with an Ohm meter between pins 1,3 when the power is off. It should be spanning a big range from zero to near its kΩ value (VR//VRR). It needs to be set very low near zero side for 5V out. Did you turn it down enough?