I just checked the size of the 1550C box I have is 4.5″x 3.5″x 2.19″
I googled it again and got this (The Hammond 1550C is 4.53 in x 3.54 in x 2.01 in (115 mm x 90 mm x 51 mm). It weighs 0.49 lbs (0.22 kg)
Maybe this was a substitute of the The Hammond 1590WB is 4.43 in x 2.38 in x 1.22 in (113 mm x 60 mm x 31 mm).
Larry – N7LUF
@larry_n7luf Well…As far as I remember the 1550C is for the “Cap Leak.” and surely fits the “Sift” project too, so you should be ok. But no worries, they are all respectable boxes and I’m positively sure that some of the future projects will use those too. So,…rest assured. 🙂
@larry_n7luf An early iteration of the Cap Leak. Tester uses 1550WC but i think that “W” might stand for having a gasket and 1550C does not or the other way around I’m not 100% sure, otherwise the look to be identical.
I have built the SIFT project twice. It was my first build using toner transfer and microscope component installation. The first build performed poorly. It would only detect the foil side on low value caps, it had to be on high gain with the gain pot at max to detect anything. In other words much lower sensitivity than Mr C’s device. I then re-built the project from scratch, exactly as given in the design docs, with the same result. I used components from main line manufacturers, from reputable suppliers, all 1% resistors, tested all 5089 transistors for high/similar hfe. Scrupulously cleaned flux after soldering. Repeating the analysis of the amplifier signal path (see Video #50), my collector voltages are consistently less than Mr C’s values, at all three stages.
So I am looking for ways to improve my sensitivity so that my device performs as Mr C’s device does in Video #50. At the end of that video he suggests that higher emitter cap values will increase gain, but may lead to oscillation. What would be the indications that oscillation is occurring? Any suggestions on how to approach this issue?
@ab8151 Wish I could help you, as I have that build on my bench and waiting for some parts.
Larry – N7LUF
@ab8151 I.ve built the SIFT twice (myself) once on the breadboard using TH classic components and second time using SMD components and I can confirm that the project works as advertised no problems whatsoever. If anything It has a little too much gain if you ask me. In other words I can only use the pot up to 50% cos otherwise the amplification is over the roof !. If you’ve strictly followed the instructions and used proper genuine components it should definitely work (of that I’m sure) perhaps it must be a human error somewhere. Some important points to be aware of:
1. watch out at the way you do the wiring but especially the potentiometer in relation with the toggle switch. it is kind of confusing at first and….who knows the culprit could be right there !
2. make sure you have the right value pot and that you measure the actual value of it. Make sure you have the right kind of toggle switch and that it works because certain switches of that kind are know to develop a high resistance fault (after soldering the wires to them) is best to be fast/quick when soldering those terminals.
3. make sure you triple check every resistor value and that has been soldered in the right place. it is extremely easy to solder them in the wrong spot. It has happen to me many times. Also pay close attention to diodes and tantalum caps polarity. Again, very easy to make mistakes like that .
4. make sure you have the stated value for that massive capacitor across the supply. (Just a thought!)
5. And ultimately power supply. Make sure that the battery has enough juice left in it and that the voltage doesn’t “sag” / “drop” while in use. So if you’re not sure I would use a proper lab power supply set to the right voltage and minimum of 500mA while doing the testing.
NOTE: after all the whole project is just a high gain amplifier coupled with a switching circuit. So it should be fairly easy to troubleshoot really
@ovi4 I was just thinking about the DPDT SWITCH 6 pole, is it an on/off/on or on/on/on and is it two or three Position switch.
I do believe the SPDT switch is a two position switch.
I will have to go back to the video, as I remember he did talk about the type of switch to use.
He did one say one could use, 100K Potentiometer (you choose size) –X1 (with optional on/off switch).
With that type or switch, where would the 120 ohm resistor connect too and you only have two poles?
Larry – N7LUF
@ovi4 I was just thinking about the DPDT SWITCH 6 pole, is it an on/off/on or on/on/on and is it two or three Position switch.
I do believe the SPDT switch is a two position switch.
I will have to go back to the video, as I remember he did talk about the type of switch to use.
He did one say one could use, 100K Potentiometer (you choose size) –X1 (with optional on/off switch).
With that type or switch, where would the 120 ohm resistor connect too and you only have two poles?
After watching the video it is both are 2 Position switch on/on.
Larry – N7LUF
I am hoping that someone in the forum might be able to help me troubleshoot a problem with my SIFT project. Specifically, I am hoping that someone with a good SIFT device might have a set of voltage readings from the transistors in the amplifier section. As an example of what I am looking for, I have given the 5089 transistor voltage readings from my own SIFT project:
Initial conditions: Device supply voltage = 8.99 v, no signal applied to the device test inputs, all voltages are dc and with respect to device ground.
Amplifier #1 5089: Collector = 5.20 v, base = 0.93 v, emitter = 0.34 v
Amplifier #2 5089: Collector = 5.20 v, base = 0.93 v, emitter = 0.34 v
Amplifier #3 5089: Collector = 5.16 +/- 0.1 v, base = 0.93 v, emitter = 0.34 v (collector voltage moves a bit as the switching section cycles)
Thank you in advance for any assistance.
@ab8151 Here we go: all measurements have been taken at the time of posting.
My build is an adaptation of the original PCB : – because I choose a smaller Hammond box ( that I already had) I had to redesign the PCB (about 20% smaller) so it could fit the box!
Initial conditions: Supply voltage = 9.18V – (Brand New Duracell Battery!) voltage level measured while the device was switched on !.
No DUT attached. All voltages measured with respect to GND.
Tester used: FLUKE 87 V (0.025 % DC accuracy!) with the calibration certificate still in date!.
A1 : C = 5.15 v, B= 0.93 v, E= 0.34 v
A2 : C = 5.15 v, B= 0.93 v, emitter = 0.34 v
A3 : C = 5.16V (+/- 0.15), B= 0.93V, E= 0.34V
Thank you very much Ovi for taking the time to make those measurements. Your help is appreciated.
While I have checked my amplifier resistors multiple times before, this seemed like a different (if not fruitful) approach. The results seem to verify that my amplifier resistor network is good, with the possible exception of the two 10k resistors between stages 1 & 2, and between stages 2 & 3.